#include <bits/stdc++.h>   using namespace std;   vector<long long> v;   long long x, y, z, a, b, c, sum, ans, total, t, cnt, n, m, k, p, kase;   string s1, s2;   map<long long, long long> mp;   set<long long> s;   map<long long, long long>::iterator itr1, ptr1;   set<long long>::iterator itr, ptr;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     cin >> t;     while (t--) {       long long x1, x2, y1, y2;       cin >> x1 >> y1 >> x2 >> y2;       ans = abs(x1 - x2);       ans *= abs(y1 - y2);       cout << ans + 1 << endl;     }     return 0;   }   