#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  unsigned long long t;
  cin >> t;
  while (t--) {
    unsigned long long x1, x2, y1, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    if (x1 == x2 || y1 == y2) {
      cout << 1 << "\n";
    } else {
      unsigned long long d = x2 - x1;
      unsigned long long r = y2 - y1;
      cout << d * r + 1 << "\n";
    }
  }
  return 0;
}
