func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int n;     cin >> n;     int x1, y1, x2, y2;     int sum = 0;     for (int i = 0; i < n; ++i) {       cin >> x1 >> y1 >> x2 >> y2;       sum += (abs(x2 - x1) + 1) * (abs(y2 - y1) + 1);     }     cout << sum;     return 0;   }   