func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     int r, c, n, k;     cin >> r >> c >> n >> k;     int tab[r][c];     for (int i = 0; i < r; i++)       for (int j = 0; j < c; j++) tab[i][j] = 0;     for (int i = 0; i < n; i++) {       int x, y;       cin >> x >> y;       --x;       --y;       tab[x][y] = 1;     }     int wyn = 0;     for (int x1 = 0; x1 < r; x1++)       for (int y1 = 0; y1 < c; y1++)         for (int x2 = x1; x2 < r; x2++)           for (int y2 = y1; y2 < c; y2++) {             int v = 0;             for (int i = x1; i <= x2; i++)               for (int j = y1; j <= y2; j++) v += tab[i][j];             if (v >= k) wyn++;           }     cout << wyn;   }   