#include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(false);     cin.tie(NULL);     int t;     cin >> t;     while (t--) {       long long a, b, x, y;       cin >> a >> b >> x >> y;       long long distX = x - a, distY = y - b;       cout << distX * distY + 1 <<   n ;     }   }   