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const int N = 1e5 + 5;
vii v[N];
int par[N];
int p[N];
int vis[N];
int links;
 
void dfs(int node, int pr) {
  par[node] = pr;
  int x = 1;
  for (auto &i : v[node]) {
    if (i ^ pr)  dfs(i, node);
  }
}
 
int power(int n, int p) {
  int r = 1;
  while (p) {
    if (p & 1) r *= n;
    r %= mod;
    n *= n;
    n %= mod;
    p /= 2LL;
  }
  return r;
}
 
void dfss(int u, int pr, set<int>&s) {
  vis[u] = 1;
  for (auto &i : v[u]) {
    if (i ^ pr and !s.count(i)) {
      links++;
      dfss(i, u, s);
    }
  }
}
 
void solve()
{
  int n, q;
  cin >> n >> q;
 
  p[0] = 1;
  fo(i, 1, n) p[i] = (p[i - 1] * 2LL) % mod;
 
  fo(i, 0, n - 2) {
    int x, y;
    cin >> x >> y;
    v[x].pb(y);
    v[y].pb(x);
  }
 
  while (q--) {
    int x, y;
    cin >> x >> y;
    dfs(x, x);
    set<int>s;
    while (y ^ x) {
      s.insert(y);
      y = par[y];
    }
    s.insert(x);
 
    links = 0;
    fo(i, 1, n) vis[i] = 0;
    fo(i, 1, n) {
      if (!s.count(i) and !vis[i]) dfss(i, i, s);
    }
    int ans = power(2LL, links);
    cout << ans << endl;
  }
}
 

prog.cpp:2:1: error: ‘vii’ does not name a type; did you mean ‘void’?
 vii v[N];
 ^~~
 void
prog.cpp: In function ‘void dfs(int, int)’:
prog.cpp:11:18: error: ‘v’ was not declared in this scope
   for (auto &i : v[node]) {
                  ^
prog.cpp: In function ‘int power(int, int)’:
prog.cpp:20:10: error: ‘mod’ was not declared in this scope
     r %= mod;
          ^~~
prog.cpp: At global scope:
prog.cpp:28:26: error: ‘set’ has not been declared
 void dfss(int u, int pr, set<int>&s) {
                          ^~~
prog.cpp:28:29: error: expected ‘,’ or ‘...’ before ‘<’ token
 void dfss(int u, int pr, set<int>&s) {
                             ^
prog.cpp: In function ‘void dfss(int, int, int)’:
prog.cpp:30:18: error: ‘v’ was not declared in this scope
   for (auto &i : v[u]) {
                  ^
prog.cpp:31:21: error: ‘s’ was not declared in this scope
     if (i ^ pr and !s.count(i)) {
                     ^
prog.cpp: In function ‘void solve()’:
prog.cpp:41:3: error: ‘cin’ was not declared in this scope
   cin >> n >> q;
   ^~~
prog.cpp:44:6: error: ‘i’ was not declared in this scope
   fo(i, 1, n) p[i] = (p[i - 1] * 2LL) % mod;
      ^
prog.cpp:44:3: error: ‘fo’ was not declared in this scope
   fo(i, 1, n) p[i] = (p[i - 1] * 2LL) % mod;
   ^~
prog.cpp:57:5: error: ‘set’ was not declared in this scope
     set<int>s;
     ^~~
prog.cpp:57:9: error: expected primary-expression before ‘int’
     set<int>s;
         ^~~
prog.cpp:59:7: error: ‘s’ was not declared in this scope
       s.insert(y);
       ^
prog.cpp:62:5: error: ‘s’ was not declared in this scope
     s.insert(x);
     ^
prog.cpp:70:5: error: ‘cout’ was not declared in this scope
     cout << ans << endl;
     ^~~~
prog.cpp:70:20: error: ‘endl’ was not declared in this scope
     cout << ans << endl;
                    ^~~~
prog.cpp:70:20: note: suggested alternative: ‘enum’
     cout << ans << endl;
                    ^~~~
                    enum

Standard output is empty