#include <bits/stdc++.h>
using namespace std;
vector<int> prime_Numbers;
bool primes[1000005];
void prime(int n) {
  for (int i = 2; i <= n; i++) primes[i] = true;
  for (int i = 2; i <= n; i++) {
    if (primes[i] == true) {
      prime_Numbers.push_back(i);
      for (int j = i + i; j <= n; j += i) primes[j] = false;
    }
  }
}
int fib(int n) {
  if (n == 1 || n == 0) return n;
  return fib(n - 1) + fib(n - 2);
}
long long fastpower(int b, int p) {
  if (p == 0) return 1;
  long long term = fastpower(b, p / 2);
  term *= term;
  if (p % 2 != 0) return term *= b;
  return term;
}
int main() {
  int t;
  cin >> t;
  while (t--) {
    long long a, b, x, y, z[4] = {0};
    cin >> a >> b >> x >> y;
    if (b - (y + 1) > 0) z[0] = abs(b - (y + 1)) * a;
    z[1] = abs(y) * a;
    if (a - (x + 1) > 0) z[2] = abs(a - (x + 1)) * b;
    z[3] = abs(x) * b;
    sort(z, z + 4);
    cout << z[3] << endl;
  }
  return 0;
}
