#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int Tc;
  cin >> Tc;
  while (Tc > 0) {
    Tc--;
    long long int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    long long int nx = abs(x1 - x2);
    long long int ny = abs(y1 - y2);
    cout << (nx * ny + 1) << endl;
  }
  return 0;
}
