func_code_string: #include <bits/stdc++.h>   using namespace std;   bool comp(int x, int y) { return x > y; }   int dx[] = {0, 0, 1, -1};   int dy[] = {1, -1, 0, 0};   long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }   int main() {     int n;     cin >> n;     vector<pair<int, int> > a(n);     for (int i = 0; i < n; i++) {       int x, y;       cin >> x >> y;       a[i] = make_pair(x, y);     }     int res = 0;     for (int i = 0; i < n; i++) {       int x1 = a[i].first;       int y1 = a[i].second;       int upper = 0, lower = 0, right = 0, left = 0;       for (int j = 0; j < n; j++) {         if (i != j) {           int x2 = a[j].first;           int y2 = a[j].second;           if (x2 > x1 && y1 == y2) right++;           if (x2 < x1 && y1 == y2) left++;           if (x1 == x2 && y2 > y1) upper++;           if (x1 == x2 && y2 < y1) lower++;         }       }       if (upper >= 1 && lower >= 1 && right >= 1 && left >= 1) res++;     }     cout << res << endl;     return 0;   }   