56. C. Celex Update (Code Forces - Round 645 - Div. 2).cpp

#include <bits/stdc++.h>

using namespace std;

int main(){

    int t;
    cin >> t;
    while(t--){
        long long x1, y1, x2, y2;
        cin >> x1 >> y1 >> x2 >> y2;
        cout << (x2-x1) * (y2-y1) + 1 << "\n";
    }

}