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#include <bits/stdc++.h>
#define endl '\n'
#define MAXN 300003
using namespace std;
int n, q;
vector <int> queries;
vector <pair <int, int> > tr[MAXN << 2];
void update(int v, int l, int r, int ll, int rr, int a, int b)
{
    if (l > rr || r < ll)
        return;
    if (l >= ll && r <= rr)
    {
        tr[v].push_back({a, b});
        return;
    }
    int mid = (l + r) >> 1;
    update(v << 1, l, mid, ll, rr, a, b);
    update((v << 1) + 1, mid + 1, r, ll, rr, a, b);
}
map <pair <int, int>, int> in;
void read()
{
    cin >> n >> q;
    for (int i = 1; i <= q; i++)
    {
        string type;
        cin >> type;
        if (type == '?')
            queries.push_back(i);
        else
        {
            int a, b;
            cin >> a >> b;
            if (a > b)
                swap(a, b);
            if (type == '+')
                in[{a, b}] = i;
            else
            {
                update(1, 1, q, in[{a, b}], i, a, b);
                in.erase({a, b});
            }
        }
    }
    for (auto i: in)
        update(1, 1, q, i.second, q, i.first.first, i.first.second);
}
int par[MAXN], sz[MAXN];
stack <int> st;
int find(int ver)
{
    while (ver != par[ver])
        ver = par[ver];
    return ver;
}
void merge(int a, int b)
{
    a = find(a), b = find(b);
    if (a == b)
        return;
    if (sz[a] > sz[b])
        swap(a, b);
    par[a] = b;
    sz[b] += sz[a];
    st.push(a);
}
void rollback(int moment)
{
    while (st.size() > moment)
    {
        int curr = st.top();
        st.pop();
        sz[par[curr]] -= sz[curr];
        par[curr] = curr;
    }
}
int ans[MAXN];
void dfs(int v, int l, int r)
{
    if (l > r)
        return;
    int moment = st.size();
    for (auto i: tr[v])
        merge(i.first, i.second);
    if (l == r)
        ans[l] = cnt;
    else
    {
        int mid = (l + r) >> 1;
        dfs(v << 1, l, mid);
        dfs((v << 1) + 1, mid + 1, r);
    }
    rollback(moment);
}
void solve()
{
    for (int i = 1; i <= n; i++)
        par[i] = i, sz[i] = 1;
    dfs(1, 1, q);
    for (auto i: queries)
        cout << ans[i] << endl;
}
int main()
{
    freopen("connect.in", "r", stdin);
    freopen("connect.out", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    read();
    solve();
}
 

prog.cpp: In function ‘void read()’:
prog.cpp:29:18: error: no match for ‘operator==’ (operand types are ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ and ‘char’)
         if (type == '?')
             ~~~~~^~~~~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:940:5: note: candidate: template<class _BiIter> bool std::__cxx11::operator==(const std::__cxx11::sub_match<_BiIter>&, const std::__cxx11::sub_match<_BiIter>&)
     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:940:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1013:5: note: candidate: template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const std::__cxx11::sub_match<_BiIter>&)
     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1013:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::__cxx11::sub_match<_BiIter>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1093:5: note: candidate: template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const std::__cxx11::sub_match<_BiIter>&, std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)
     operator==(const sub_match<_Bi_iter>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1093:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1173:5: note: candidate: template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const std::__cxx11::sub_match<_BiIter>&)
     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1173:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::__cxx11::sub_match<_BiIter>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1247:5: note: candidate: template<class _Bi_iter> bool std::__cxx11::operator==(const std::__cxx11::sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)
     operator==(const sub_match<_Bi_iter>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1247:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1321:5: note: candidate: template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const std::__cxx11::sub_match<_BiIter>&)
     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1321:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::__cxx11::sub_match<_BiIter>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1401:5: note: candidate: template<class _Bi_iter> bool std::__cxx11::operator==(const std::__cxx11::sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)
     operator==(const sub_match<_Bi_iter>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1401:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1920:5: note: candidate: template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const std::__cxx11::match_results<_BiIter, _Alloc>&, const std::__cxx11::match_results<_BiIter, _Alloc>&)
     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1920:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::match_results<_BiIter, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/iosfwd:40:0,
                 from /usr/include/c++/6/ios:38,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/postypes.h:216:5: note: candidate: template<class _StateT> bool std::operator==(const std::fpos<_StateT>&, const std::fpos<_StateT>&)
     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
     ^~~~~~~~
/usr/include/c++/6/bits/postypes.h:216:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::fpos<_StateT>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:64:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_pair.h:431:5: note: candidate: template<class _T1, class _T2> constexpr bool std::operator==(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
     ^~~~~~~~
/usr/include/c++/6/bits/stl_pair.h:431:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::pair<_T1, _T2>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_iterator.h:292:5: note: candidate: template<class _Iterator> bool std::operator==(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
     operator==(const reverse_iterator<_Iterator>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:292:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_iterator.h:349:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator==(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)
     operator==(const reverse_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:349:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_iterator.h:1113:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator==(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)
     operator==(const move_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:1113:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::move_iterator<_IteratorL>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_iterator.h:1119:5: note: candidate: template<class _Iterator> bool std::operator==(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorL>&)
     operator==(const move_iterator<_Iterator>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:1119:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::move_iterator<_IteratorL>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/string:41:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/allocator.h:146:5: note: candidate: template<class _T1, class _T2> bool std::operator==(const std::allocator<_CharT>&, const std::allocator<_T2>&)
     operator==(const allocator<_T1>&, const allocator<_T2>&)
     ^~~~~~~~
/usr/include/c++/6/bits/allocator.h:146:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::allocator<_CharT>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/string:41:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/allocator.h:152:5: note: candidate: template<class _Tp> bool std::operator==(const std::allocator<_CharT>&, const std::allocator<_CharT>&)
     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
     ^~~~~~~~
/usr/include/c++/6/bits/allocator.h:152:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::allocator<_CharT>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/string:52:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/basic_string.h:5065:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/basic_string.h:5065:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/string:52:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/basic_string.h:5073:5: note: candidate: template<class _CharT> typename __gnu_cxx::__enable_if<std::__is_char<_Tp>::__value, bool>::__type std::operator==(const std::__cxx11::basic_string<_CharT>&, const std::__cxx11::basic_string<_CharT>&)
     operator==(const basic_string<_CharT>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/basic_string.h:5073:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::__cxx11::basic_string<_CharT>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/string:52:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/basic_string.h:5087:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const _CharT*, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
     operator==(const _CharT* __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/basic_string.h:5087:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const _CharT*’ and ‘std::__cxx11::basic_string<char>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/string:52:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/basic_string.h:5099:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)
     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/basic_string.h:5099:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const _CharT*’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/ios_base.h:46:0,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/system_error:284:3: note: candidate: bool std::operator==(const std::error_code&, const std::error_code&)
   operator==(const error_code& __lhs, const error_code& __rhs) noexcept
   ^~~~~~~~
/usr/include/c++/6/system_error:284:3: note:   no known conversion for argument 1 from ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ to ‘const std::error_code&’
/usr/include/c++/6/system_error:289:3: note: candidate: bool std::operator==(const std::error_code&, const std::error_condition&)
   operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
   ^~~~~~~~
/usr/include/c++/6/system_error:289:3: note:   no known conversion for argument 1 from ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ to ‘const std::error_code&’
/usr/include/c++/6/system_error:296:3: note: candidate: bool std::operator==(const std::error_condition&, const std::error_code&)
   operator==(const error_condition& __lhs, const error_code& __rhs) noexcept
   ^~~~~~~~
/usr/include/c++/6/system_error:296:3: note:   no known conversion for argument 1 from ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ to ‘const std::error_condition&’
/usr/include/c++/6/system_error:303:3: note: candidate: bool std::operator==(const std::error_condition&, const std::error_condition&)
   operator==(const error_condition& __lhs,
   ^~~~~~~~
/usr/include/c++/6/system_error:303:3: note:   no known conversion for argument 1 from ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ to ‘const std::error_condition&’
In file included from /usr/include/c++/6/bits/locale_facets.h:48:0,
                 from /usr/include/c++/6/bits/basic_ios.h:37,
                 from /usr/include/c++/6/ios:44,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/streambuf_iterator.h:204:5: note: candidate: template<class _CharT, class _Traits> bool std::operator==(const std::istreambuf_iterator<_CharT, _Traits>&, const std::istreambuf_iterator<_CharT, _Traits>&)
     operator==(const istreambuf_iterator<_CharT, _Traits>& __a,
     ^~~~~~~~
/usr/include/c++/6/bits/streambuf_iterator.h:204:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::istreambuf_iterator<_CharT, _Traits>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/ccomplex:39:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/complex:458:5: note: candidate: template<class _Tp> constexpr bool std::operator==(const std::complex<_Tp>&, const std::complex<_Tp>&)
     operator==(const complex<_Tp>& __x, const complex<_Tp>& __y)
     ^~~~~~~~
/usr/include/c++/6/complex:458:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::complex<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/ccomplex:39:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/complex:463:5: note: candidate: template<class _Tp> constexpr bool std::operator==(const std::complex<_Tp>&, const _Tp&)
     operator==(const complex<_Tp>& __x, const _Tp& __y)
     ^~~~~~~~
/usr/include/c++/6/complex:463:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::complex<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/ccomplex:39:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/complex:468:5: note: candidate: template<class _Tp> constexpr bool std::operator==(const _Tp&, const std::complex<_Tp>&)
     operator==(const _Tp& __x, const complex<_Tp>& __y)
     ^~~~~~~~
/usr/include/c++/6/complex:468:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::complex<_Tp>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/deque:64:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:68,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_deque.h:265:5: note: candidate: template<class _Tp, class _Ref, class _Ptr> bool std::operator==(const std::_Deque_iterator<_Tp, _Ref, _Ptr>&, const std::_Deque_iterator<_Tp, _Ref, _Ptr>&)
     operator==(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_deque.h:265:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Deque_iterator<_Tp, _Ref, _Ptr>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/deque:64:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:68,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_deque.h:272:5: note: candidate: template<class _Tp, class _RefL, class _PtrL, class _RefR, class _PtrR> bool std::operator==(const std::_Deque_iterator<_Tp, _Ref, _Ptr>&, const std::_Deque_iterator<_Tp, _RefR, _PtrR>&)
     operator==(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_deque.h:272:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Deque_iterator<_Tp, _Ref, _Ptr>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/deque:64:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:68,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_deque.h:2220:5: note: candidate: template<class _Tp, class _Alloc> bool std::operator==(const std::deque<_Tp, _Alloc>&, const std::deque<_Tp, _Alloc>&)
     operator==(const deque<_Tp, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_deque.h:2220:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::deque<_Tp, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/tuple:39:0,
                 from /usr/include/c++/6/functional:55,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:71,
                 from prog.cpp:1:
/usr/include/c++/6/array:241:5: note: candidate: template<class _Tp, long unsigned int _Nm> bool std::operator==(const std::array<_Tp, _Nm>&, const std::array<_Tp, _Nm>&)
     operator==(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     ^~~~~~~~
/usr/include/c++/6/array:241:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::array<_Tp, _Nm>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/functional:55:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:71,
                 from prog.cpp:1:
/usr/include/c++/6/tuple:1341:5: note: candidate: template<class ... _TElements, class ... _UElements> constexpr bool std::operator==(const std::tuple<_Elements ...>&, const std::tuple<_Elements ...>&)
     operator==(const tuple<_TElements...>& __t,
     ^~~~~~~~
/usr/include/c++/6/tuple:1341:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::tuple<_Elements ...>’
         if (type == '?')
                     ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:71:0,
                 from prog.cpp:1:
/usr/include/c++/6/functional:2193:5: note: candidate: template<class _Res, class ... _Args> bool std::operator==(const std::function<_Res(_ArgTypes ...)>&, std::nullptr_t)
     operator==(const function<_Res(_Args...)>& __f, nullptr_t) noexcept
     ^~~~~~~~
/usr/include/c++/6/functional:2193:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::function<_Res(_ArgTypes ...)>’
         if (type == '?')
                     ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:71:0,
                 from prog.cpp:1:
/usr/include/c++/6/functional:2199:5: note: candidate: template<class _Res, class ... _Args> bool std::operator==(std::nullptr_t, const std::function<_Res(_ArgTypes ...)>&)
     operator==(nullptr_t, const function<_Res(_Args...)>& __f) noexcept
     ^~~~~~~~
/usr/include/c++/6/functional:2199:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::function<_Res(_ArgTypes ...)>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/locale_conv.h:41:0,
                 from /usr/include/c++/6/locale:43,
                 from /usr/include/c++/6/iomanip:43,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:72,
                 from prog.cpp:1:
/usr/include/c++/6/bits/unique_ptr.h:650:5: note: candidate: template<class _Tp, class _Dp, class _Up, class _Ep> bool std::operator==(const std::unique_ptr<_Tp, _Dp>&, const std::unique_ptr<_Up, _Ep>&)
     operator==(const unique_ptr<_Tp, _Dp>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/unique_ptr.h:650:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::unique_ptr<_Tp, _Dp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/locale_conv.h:41:0,
                 from /usr/include/c++/6/locale:43,
                 from /usr/include/c++/6/iomanip:43,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:72,
                 from prog.cpp:1:
/usr/include/c++/6/bits/unique_ptr.h:656:5: note: candidate: template<class _Tp, class _Dp> bool std::operator==(const std::unique_ptr<_Tp, _Dp>&, std::nullptr_t)
     operator==(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
     ^~~~~~~~
/usr/include/c++/6/bits/unique_ptr.h:656:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::unique_ptr<_Tp, _Dp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/locale_conv.h:41:0,
                 from /usr/include/c++/6/locale:43,
                 from /usr/include/c++/6/iomanip:43,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:72,
                 from prog.cpp:1:
/usr/include/c++/6/bits/unique_ptr.h:661:5: note: candidate: template<class _Tp, class _Dp> bool std::operator==(std::nullptr_t, const std::unique_ptr<_Tp, _Dp>&)
     operator==(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
     ^~~~~~~~
/usr/include/c++/6/bits/unique_ptr.h:661:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::unique_ptr<_Tp, _Dp>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/iterator:66:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:77,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stream_iterator.h:130:5: note: candidate: template<class _Tp, class _CharT, class _Traits, class _Dist> bool std::operator==(const std::istream_iterator<_Tp, _CharT, _Traits, _Dist>&, const std::istream_iterator<_Tp, _CharT, _Traits, _Dist>&)
     operator==(const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stream_iterator.h:130:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::istream_iterator<_Tp, _CharT, _Traits, _Dist>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/list:63:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:79,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_list.h:287:5: note: candidate: template<class _Val> bool std::operator==(const std::_List_iterator<_Tp>&, const std::_List_const_iterator<_Tp>&)
     operator==(const _List_iterator<_Val>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_list.h:287:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_List_iterator<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/list:63:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:79,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_list.h:1853:5: note: candidate: template<class _Tp, class _Alloc> bool std::operator==(const std::__cxx11::list<_Tp, _Alloc>&, const std::__cxx11::list<_Tp, _Alloc>&)
     operator==(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
     ^~~~~~~~
/usr/include/c++/6/bits/stl_list.h:1853:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::list<_Tp, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/map:60:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:81,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_tree.h:328:5: note: candidate: template<class _Val> bool std::operator==(const std::_Rb_tree_iterator<_Tp>&, const std::_Rb_tree_const_iterator<_Val>&)
     operator==(const _Rb_tree_iterator<_Val>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_tree.h:328:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Rb_tree_iterator<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/map:60:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:81,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_tree.h:1282:5: note: candidate: template<class _Key, class _Val, class _KeyOfValue, class _Compare, class _Alloc> bool std::operator==(const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&, const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&)
     operator==(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_tree.h:1282:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/map:61:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:81,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_map.h:1307:5: note: candidate: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const std::map<_Key, _Tp, _Compare, _Alloc>&, const std::map<_Key, _Tp, _Compare, _Alloc>&)
     operator==(const map<_Key, _Tp, _Compare, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_map.h:1307:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::map<_Key, _Tp, _Compare, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/map:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:81,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_multimap.h:972:5: note: candidate: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const std::multimap<_Key, _Tp, _Compare, _Alloc>&, const std::multimap<_Key, _Tp, _Compare, _Alloc>&)
     operator==(const multimap<_Key, _Tp, _Compare, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_multimap.h:972:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::multimap<_Key, _Tp, _Compare, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/shared_ptr.h:52:0,
                 from /usr/include/c++/6/memory:82,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:82,
                 from prog.cpp:1:
/usr/include/c++/6/bits/shared_ptr_base.h:1186:5: note: candidate: template<class _Tp1, class _Tp2, __gnu_cxx::_Lock_policy _Lp> bool std::operator==(const std::__shared_ptr<_Tp1, _Lp>&, const std::__shared_ptr<_Tp2, _Lp>&)
     operator==(const __shared_ptr<_Tp1, _Lp>& __a,
     ^~~~~~~~
/usr/include/c++/6/bits/shared_ptr_base.h:1186:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__shared_ptr<_Tp1, _Lp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/shared_ptr.h:52:0,
                 from /usr/include/c++/6/memory:82,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:82,
                 from prog.cpp:1:
/usr/include/c++/6/bits/shared_ptr_base.h:1192:5: note: candidate: template<class _Tp, __gnu_cxx::_Lock_policy _Lp> bool std::operator==(const std::__shared_ptr<_Tp, _Lp>&, std::nullptr_t)
     operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
     ^~~~~~~~
/usr/include/c++/6/bits/shared_ptr_base.h:1192:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__shared_ptr<_Tp, _Lp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/shared_ptr.h:52:0,
                 from /usr/include/c++/6/memory:82,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:82,
                 from prog.cpp:1:
/usr/include/c++/6/bits/shared_ptr_base.h:1197:5: note: candidate: template<class _Tp, __gnu_cxx::_Lock_policy _Lp> bool std::operator==(std::nullptr_t, const std::__shared_ptr<_Tp, _Lp>&)
     operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
     ^~~~~~~~
/usr/include/c++/6/bits/shared_ptr_base.h:1197:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::__shared_ptr<_Tp, _Lp>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/memory:82:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:82,
                 from prog.cpp:1:
/usr/include/c++/6/bits/shared_ptr.h:336:5: note: candidate: template<class _Tp1, class _Tp2> bool std::operator==(const std::shared_ptr<_Tp1>&, const std::shared_ptr<_Tp2>&)
     operator==(const shared_ptr<_Tp1>& __a,
     ^~~~~~~~
/usr/include/c++/6/bits/shared_ptr.h:336:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::shared_ptr<_Tp1>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/memory:82:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:82,
                 from prog.cpp:1:
/usr/include/c++/6/bits/shared_ptr.h:342:5: note: candidate: template<class _Tp> bool std::operator==(const std::shared_ptr<_Tp1>&, std::nullptr_t)
     operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
     ^~~~~~~~
/usr/include/c++/6/bits/shared_ptr.h:342:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::shared_ptr<_Tp1>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/memory:82:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:82,
                 from prog.cpp:1:
/usr/include/c++/6/bits/shared_ptr.h:347:5: note: candidate: template<class _Tp> bool std::operator==(std::nullptr_t, const std::shared_ptr<_Tp1>&)
     operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
     ^~~~~~~~
/usr/include/c++/6/bits/shared_ptr.h:347:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::shared_ptr<_Tp1>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/vector:64:0,
                 from /usr/include/c++/6/queue:61,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:86,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_vector.h:1509:5: note: candidate: template<class _Tp, class _Alloc> bool std::operator==(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&)
     operator==(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
     ^~~~~~~~
/usr/include/c++/6/bits/stl_vector.h:1509:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::vector<_Tp, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/queue:64:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:86,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_queue.h:298:5: note: candidate: template<class _Tp, class _Seq> bool std::operator==(const std::queue<_Tp, _Seq>&, const std::queue<_Tp, _Seq>&)
     operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
     ^~~~~~~~
/usr/include/c++/6/bits/stl_queue.h:298:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::queue<_Tp, _Seq>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/set:61:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:87,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_set.h:840:5: note: candidate: template<class _Key, class _Compare, class _Alloc> bool std::operator==(const std::set<_Key, _Compare, _Alloc>&, const std::set<_Key, _Compare, _Alloc>&)
     operator==(const set<_Key, _Compare, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_set.h:840:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::set<_Key, _Compare, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/set:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:87,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_multiset.h:823:5: note: candidate: template<class _Key, class _Compare, class _Alloc> bool std::operator==(const std::multiset<_Key, _Compare, _Alloc>&, const std::multiset<_Key, _Compare, _Alloc>&)
     operator==(const multiset<_Key, _Compare, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_multiset.h:823:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::multiset<_Key, _Compare, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/stack:61:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:89,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_stack.h:275:5: note: candidate: template<class _Tp, class _Seq> bool std::operator==(const std::stack<_Tp, _Seq>&, const std::stack<_Tp, _Seq>&)
     operator==(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
     ^~~~~~~~
/usr/include/c++/6/bits/stl_stack.h:275:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::stack<_Tp, _Seq>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/valarray:587:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95,
                 from prog.cpp:1:
/usr/include/c++/6/bits/valarray_after.h:414:5: note: candidate: template<class _Dom1, class _Dom2> std::_Expr<std::_BinClos<std::__equal_to, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__equal_to, typename _Dom1::value_type>::result_type> std::operator==(const std::_Expr<_Dom1, typename _Dom1::value_type>&, const std::_Expr<_Dom2, typename _Dom2::value_type>&)
     _DEFINE_EXPR_BINARY_OPERATOR(==, __equal_to)
     ^
/usr/include/c++/6/bits/valarray_after.h:414:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Expr<_Dom1, typename _Dom1::value_type>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/valarray:587:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95,
                 from prog.cpp:1:
/usr/include/c++/6/bits/valarray_after.h:414:5: note: candidate: template<class _Dom> std::_Expr<std::_BinClos<std::__equal_to, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__equal_to, typename _Dom1::value_type>::result_type> std::operator==(const std::_Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)
     _DEFINE_EXPR_BINARY_OPERATOR(==, __equal_to)
     ^
/usr/include/c++/6/bits/valarray_after.h:414:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Expr<_Dom1, typename _Dom1::value_type>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/valarray:587:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95,
                 from prog.cpp:1:
/usr/include/c++/6/bits/valarray_after.h:414:5: note: candidate: template<class _Dom> std::_Expr<std::_BinClos<std::__equal_to, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__equal_to, typename _Dom1::value_type>::result_type> std::operator==(const typename _Dom::value_type&, const std::_Expr<_Dom1, typename _Dom1::value_type>&)
     _DEFINE_EXPR_BINARY_OPERATOR(==, __equal_to)
     ^
/usr/include/c++/6/bits/valarray_after.h:414:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::_Expr<_Dom1, typename _Dom1::value_type>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/valarray:587:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95,
                 from prog.cpp:1:
/usr/include/c++/6/bits/valarray_after.h:414:5: note: candidate: template<class _Dom> std::_Expr<std::_BinClos<std::__equal_to, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__equal_to, typename _Dom1::value_type>::result_type> std::operator==(const std::_Expr<_Dom1, typename _Dom1::value_type>&, const std::valarray<typename _Dom::value_type>&)
     _DEFINE_EXPR_BINARY_OPERATOR(==, __equal_to)
     ^
/usr/include/c++/6/bits/valarray_after.h:414:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Expr<_Dom1, typename _Dom1::value_type>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/valarray:587:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95,
                 from prog.cpp:1:
/usr/include/c++/6/bits/valarray_after.h:414:5: note: candidate: template<class _Dom> std::_Expr<std::_BinClos<std::__equal_to, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__equal_to, typename _Dom1::value_type>::result_type> std::operator==(const std::valarray<typename _Dom::value_type>&, const std::_Expr<_Dom1, typename _Dom1::value_type>&)
     _DEFINE_EXPR_BINARY_OPERATOR(==, __equal_to)
     ^
/usr/include/c++/6/bits/valarray_after.h:414:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::_Expr<_Dom1, typename _Dom1::value_type>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95:0,
                 from prog.cpp:1:
/usr/include/c++/6/valarray:1179:1: note: candidate: template<class _Tp> std::_Expr<std::_BinClos<std::__equal_to, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__equal_to, _Tp>::result_type> std::operator==(const std::valarray<_Tp>&, const std::valarray<_Tp>&)
 _DEFINE_BINARY_OPERATOR(==, __equal_to)
 ^
/usr/include/c++/6/valarray:1179:1: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::valarray<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95:0,
                 from prog.cpp:1:
/usr/include/c++/6/valarray:1179:1: note: candidate: template<class _Tp> std::_Expr<std::_BinClos<std::__equal_to, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__equal_to, _Tp>::result_type> std::operator==(const std::valarray<_Tp>&, const _Tp&)
 _DEFINE_BINARY_OPERATOR(==, __equal_to)
 ^
/usr/include/c++/6/valarray:1179:1: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::valarray<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:95:0,
                 from prog.cpp:1:
/usr/include/c++/6/valarray:1179:1: note: candidate: template<class _Tp> std::_Expr<std::_BinClos<std::__equal_to, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__equal_to, _Tp>::result_type> std::operator==(const _Tp&, const std::valarray<_Tp>&)
 _DEFINE_BINARY_OPERATOR(==, __equal_to)
 ^
/usr/include/c++/6/valarray:1179:1: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   mismatched types ‘const std::valarray<_Tp>’ and ‘char’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/forward_list:38:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:104,
                 from prog.cpp:1:
/usr/include/c++/6/bits/forward_list.h:257:5: note: candidate: template<class _Tp> bool std::operator==(const std::_Fwd_list_iterator<_Tp>&, const std::_Fwd_list_const_iterator<_Tp>&)
     operator==(const _Fwd_list_iterator<_Tp>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/forward_list.h:257:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::_Fwd_list_iterator<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/forward_list:40:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:104,
                 from prog.cpp:1:
/usr/include/c++/6/bits/forward_list.tcc:375:5: note: candidate: template<class _Tp, class _Alloc> bool std::operator==(const std::forward_list<_Tp, _Alloc>&, const std::forward_list<_Tp, _Alloc>&)
     operator==(const forward_list<_Tp, _Alloc>& __lx,
     ^~~~~~~~
/usr/include/c++/6/bits/forward_list.tcc:375:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::forward_list<_Tp, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/random:51:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:108,
                 from prog.cpp:1:
/usr/include/c++/6/bits/random.tcc:1878:5: note: candidate: template<class _RealType1> bool std::operator==(const std::normal_distribution<_RealType>&, const std::normal_distribution<_RealType>&)
     operator==(const std::normal_distribution<_RealType>& __d1,
     ^~~~~~~~
/usr/include/c++/6/bits/random.tcc:1878:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::normal_distribution<_RealType>’
         if (type == '?')
                     ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:111:0,
                 from prog.cpp:1:
/usr/include/c++/6/scoped_allocator:456:5: note: candidate: template<class _OutA1, class _OutA2, class ... _InA> bool std::operator==(const std::scoped_allocator_adaptor<_OutA1, _InA ...>&, const std::scoped_allocator_adaptor<_InnerHead, _InnerTail ...>&)
     operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
     ^~~~~~~~
/usr/include/c++/6/scoped_allocator:456:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::scoped_allocator_adaptor<_OutA1, _InA ...>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/unordered_map:48:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:117,
                 from prog.cpp:1:
/usr/include/c++/6/bits/unordered_map.h:1768:5: note: candidate: template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc> bool std::operator==(const std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>&, const std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>&)
     operator==(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/unordered_map.h:1768:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/unordered_map:48:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:117,
                 from prog.cpp:1:
/usr/include/c++/6/bits/unordered_map.h:1780:5: note: candidate: template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc> bool std::operator==(const std::unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>&, const std::unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>&)
     operator==(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/unordered_map.h:1780:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/unordered_set:48:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:118,
                 from prog.cpp:1:
/usr/include/c++/6/bits/unordered_set.h:1411:5: note: candidate: template<class _Value, class _Hash, class _Pred, class _Alloc> bool std::operator==(const std::unordered_set<_Value, _Hash, _Pred, _Alloc>&, const std::unordered_set<_Value, _Hash, _Pred, _Alloc>&)
     operator==(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/unordered_set.h:1411:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::unordered_set<_Value, _Hash, _Pred, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/unordered_set:48:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:118,
                 from prog.cpp:1:
/usr/include/c++/6/bits/unordered_set.h:1423:5: note: candidate: template<class _Value, class _Hash, class _Pred, class _Alloc> bool std::operator==(const std::unordered_multiset<_Value, _Hash, _Pred, _Alloc>&, const std::unordered_multiset<_Value, _Hash, _Pred, _Alloc>&)
     operator==(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/unordered_set.h:1423:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::unordered_multiset<_Value, _Hash, _Pred, _Alloc>’
         if (type == '?')
                     ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/c++allocator.h:33:0,
                 from /usr/include/c++/6/bits/allocator.h:46,
                 from /usr/include/c++/6/string:41,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/ext/new_allocator.h:139:5: note: candidate: template<class _Tp> bool __gnu_cxx::operator==(const __gnu_cxx::new_allocator<_Tp>&, const __gnu_cxx::new_allocator<_Tp>&)
     operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
     ^~~~~~~~
/usr/include/c++/6/ext/new_allocator.h:139:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const __gnu_cxx::new_allocator<_Tp>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_iterator.h:863:5: note: candidate: template<class _Iterator, class _Container> bool __gnu_cxx::operator==(const __gnu_cxx::__normal_iterator<_Iterator, _Container>&, const __gnu_cxx::__normal_iterator<_Iterator, _Container>&)
     operator==(const __normal_iterator<_Iterator, _Container>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:863:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const __gnu_cxx::__normal_iterator<_Iterator, _Container>’
         if (type == '?')
                     ^~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from prog.cpp:1:
/usr/include/c++/6/bits/stl_iterator.h:856:5: note: candidate: template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator==(const __gnu_cxx::__normal_iterator<_IteratorL, _Container>&, const __gnu_cxx::__normal_iterator<_IteratorR, _Container>&)
     operator==(const __normal_iterator<_IteratorL, _Container>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:856:5: note:   template argument deduction/substitution failed:
prog.cpp:29:21: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const __gnu_cxx::__normal_iterator<_IteratorL, _Container>’
         if (type == '?')
                     ^~~
prog.cpp:37:22: error: no match for ‘operator==’ (operand types are ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ and ‘char’)
             if (type == '+')
                 ~~~~~^~~~~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:940:5: note: candidate: template<class _BiIter> bool std::__cxx11::operator==(const std::__cxx11::sub_match<_BiIter>&, const std::__cxx11::sub_match<_BiIter>&)
     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:940:5: note:   template argument deduction/substitution failed:
prog.cpp:37:25: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
             if (type == '+')
                         ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1013:5: note: candidate: template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const std::__cxx11::sub_match<_BiIter>&)
     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1013:5: note:   template argument deduction/substitution failed:
prog.cpp:37:25: note:   mismatched types ‘const std::__cxx11::sub_match<_BiIter>’ and ‘char’
             if (type == '+')
                         ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1093:5: note: candidate: template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const std::__cxx11::sub_match<_BiIter>&, std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)
     operator==(const sub_match<_Bi_iter>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1093:5: note:   template argument deduction/substitution failed:
prog.cpp:37:25: note:   ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
             if (type == '+')
                         ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:110,
                 from prog.cpp:1:
/usr/include/c++/6/bits/regex.h:1173:5: note: candidate: template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const std::__cxx11::sub_match<_BiIter>&)
     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/regex.h:1173:5: note:   template argument deduction/substitution failed:
prog.cpp:37:25: note:   mismatched types ‘const std::__cxx11::sub_match<_BiIter>’ and ‘char’
             if (type == '+')
                         ^~~
In file included from /usr/include/c++/6/regex:62:0,
                 

Standard output is empty