func_code_string: #include <bits/stdc++.h>   using namespace std;   long l[101][101], n, i, j;   int main() {     cin >> n;     int x1, y1, x2, y2;     while (n--) {       cin >> x1 >> y1 >> x2 >> y2;       for (i = x1; i <= x2; i++)         for (j = y1; j <= y2; j++) l[i][j]++;     }     long long res = 0;     for (i = 1; i <= 100; i++)       for (j = 1; j <= 100; j++) res += l[i][j];     cout << res;   }   