func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, k, r, c;   vector<string> grip;   int main() {     grip.clear();     cin >> r >> c >> n >> k;     string ful =   ;     for (int i = 0; i < c; i++) ful +=  . ;     for (int i = 0; i < r; i++) grip.push_back(ful);     for (int i = 0; i < n; i++) {       int y, x;       cin >> y >> x;       y--, x--;       grip[y][x] =  # ;     }     int ans = 0;     for (int il = 0; il < r; il++) {       for (int ir = il; ir < r; ir++) {         for (int jl = 0; jl < c; jl++) {           for (int jr = jl; jr < c; jr++) {             int con = 0;             for (int p = il; p <= ir; p++) {               for (int q = jl; q <= jr; q++)                 if (grip[p][q] ==  # ) con++;             }             if (con >= k) ans++;           }         }       }     }     cout << ans << endl;   }   