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