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  1.  
  2. #include <iostream>
  3. #include <vector>
  4. #include <algorithm>
  5. #include <queue>
  6. #include <map>
  7. #include <set>
  8. #include <bits/stdc++.h>
  9. using namespace std;
  10. #include <ext/pb_ds/assoc_container.hpp>
  11. using namespace __gnu_pbds;
  12. template <class T>
  13. using orderStaticTree =
  14.     tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
  15.  
  16. #define ll long long
  17.  
  18. #define saleh                         \
  19.     ios_base::sync_with_stdio(false); \
  20.     cin.tie(nullptr);
  21.  
  22. const int md = 1e9 + 7;
  23. #define ll long long
  24.  
  25. const ll remo = -1e18;
  26.  
  27. int main()
  28. {
  29.     saleh;
  30.     int n;
  31.     cin >> n;
  32.     vector<int> v(n);
  33.     for (auto &i : v)
  34.         cin >> i;
  35.  
  36.     vector<bool> is_prime(1000000 + 100, true);
  37.     is_prime[0] = is_prime[1] = false;
  38.  
  39.     for (int i = 2; i * i <= 1000000 + 100; ++i)
  40.     {
  41.         if (is_prime[i])
  42.         {
  43.             for (int j = i * i; j <= 1000000 + 100; j += i)
  44.                 is_prime[j] = false;
  45.         }
  46.     }
  47.  
  48.     int ans = 0;
  49.     for (auto i : v)
  50.     {
  51.         if (is_prime[i])
  52.             continue;
  53.         if (i & 1)
  54.         {
  55.             if (is_prime[i - 2])
  56.                 ++ans;
  57.             else
  58.                 ans += 2;
  59.         }
  60.         else
  61.             ++ans;
  62.     }
  63.     cout << ans << endl;
  64.  
  65.     return 0;
  66. }
Success #stdin #stdout 0.01s 5304KB
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https://ideone.com/ljO7zu
language:
C++ (gcc 8.3)
created:
6 days ago
visibility:
public

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