func_code_string: #include <bits/stdc++.h>   using namespace std;   const double pi = acos(-1.0);   const double eps = 1e-11;   template <class T>   T sqr(const T &x) {     return x * x;   }   template <class T>   T lowbit(const T &x) {     return (x ^ (x - 1)) & x;   }   inline long long mlog2(long long n) {     long long c = 0;     c += 64 - __builtin_clzll(n);     return c - 1;   }   void fun(int a, int b) {     for (b = 0; b < 5; b++) a++;   }   bool arr[15][15] = {0};   int k;   bool check(int a, int b, int c, int d) {     int i, j, tp = 0;     for (i = a; i <= b; i++)       for (j = c; j <= d; j++) {         if (arr[i][j] == 1) tp++;         if (tp >= k) return 1;       }     return 0;   }   int main() {     int r, c, n, i, j, p, q, cou = 0, x, y;     cin >> r >> c >> n >> k;     for (i = 0; i < n; i++) {       cin >> x >> y;       x--;       y--;       arr[x][y] = 1;     }     for (i = 0; i < r; i++) {       for (j = i; j < r; j++) {         for (p = 0; p < c; p++) {           for (q = p; q < c; q++) {             if (check(i, j, p, q)) cou++;           }         }       }     }     cout << cou;   }   