func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int test;     cin >> test;     while (test--) {       long long x1, x2, y1, y2;       cin >> x1 >> y1 >> x2 >> y2;       cout << (long long)((x2 - x1) * (y2 - y1)) + 1 <<   n ;     }   }   