func_code_string: #include <bits/stdc++.h>   using namespace std;   bool bi[12][12];   int main() {     int a, b, c, d, e, x, y, z, n, k, N, M;     scanf( %d %d , &N, &M);     scanf( %d %d , &z, &k);     for (a = 0; a < z; a++) {       scanf( %d %d , &x, &y);       bi[x][y] = true;     }     z = 0;     for (a = 1; a <= N; a++) {       for (b = 1; b <= M; b++) {         for (c = a; c <= N; c++) {           for (d = b; d <= M; d++) {             e = 0;             for (x = a; x <= c; x++) {               for (y = b; y <= d; y++)                 if (bi[x][y]) e++;             }             if (e >= k) z++;           }         }       }     }     cout << z << endl;     return 0;   }   