#include <bits/stdc++.h>   using namespace std;   long long int max(long long int a, long long int b) {     if (a > b)       return a;     else       return b;   }   long long int min(long long int a, long long int b) {     if (a < b)       return a;     else       return b;   }   int main() {     long long int t, a, b, x, y;     cin >> t;     while (t--) {       long long int k1 = 0, k2 = 0, k3 = 0, k4 = 0, k5 = 0, k6 = 0, k7 = 0, c1,                     c2, c3, c4;       cin >> a >> b >> x >> y;       c1 = max(x, y);       c2 = min(x, y);       c3 = max(a, b);       c4 = min(a, b);       if (min(a, b) >= max(x, y)) {         k1 = (a - x - 1) * b;         k2 = x * b;         k3 = (b - y - 1) * a;         k4 = y * a;         k5 = max(k1, k2);         k6 = max(k3, k4);         k7 = max(k5, k6);       } else {         k1 = (c3 - c1 - 1) * c4;         k2 = c1 * c4;         k3 = (c4 - c2 - 1) * c3;         k4 = c2 * c3;         k5 = max(k1, k2);         k6 = max(k3, k4);         k7 = max(k5, k6);       }       cout << k7;       if (t != 0) cout << endl;     }     return 0;   }   