func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     long long int g = 0;     pair<int, int> A[1000], B[1000];     for (int i = 1; i <= n; i++) {       cin >> A[i].first >> A[i].second;       cin >> B[i].first >> B[i].second;       g += (((B[i].first - A[i].first) + 1) * ((B[i].second - A[i].second) + 1));     }     cout << g;     return 0;   }   