func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, x, y, count = 0;     cin >> n;     pair<int, int> a[3005];     set<pair<int, int>> s;     for (int i = 0; i < n; i++) {       cin >> x >> y;       a[i] = pair<int, int>(x, y);       s.insert(a[i]);     }     for (int i = 0; i < n; i++) {       for (int j = i + 1; j < n; j++) {         x = a[i].first + a[j].first;         y = a[i].second + a[j].second;         if (x % 2 == 0 && y % 2 == 0) {           x /= 2;           y /= 2;           count += (s.find(pair<int, int>(x, y)) != s.end());         }       }     }     cout << count << endl;     return 0;   }   