func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     char c = getchar();     int n = 0;     bool f = 0;     while (c <  0  || c >  9 ) {       if (c ==  - ) f = 1;       c = getchar();     }     while (c >=  0  && c <=  9 ) {       n = (n << 1) + (n << 3) + (c ^ 48);       c = getchar();     }     return f ? -n : n;   }   int r, c, n, t, x, y, ans, res;   bool m[101][101];   int main() {     r = read(), c = read(), n = read(), t = read();     for (int i = 1; i <= n; i++) {       x = read(), y = read();       m[x][y] = 1;     }     for (int i = 1; i <= r; i++)       for (int j = 1; j <= c; j++)         for (int k = i; k <= r; k++)           for (int h = j; h <= c; h++) {             res = 0;             for (int a = i; a <= k; a++)               for (int b = j; b <= h; b++)                 if (m[a][b]) res++;             if (res >= t) ans++;           }     printf( %d n , ans);     return 0;   }   