#include <bits/stdc++.h>
using namespace std;
int main() {
  long long t;
  cin >> t;
  while (t--) {
    long long x1, x2, y1, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    long long sum = abs(x2 - x1) * abs(y2 - y1) + 1;
    cout << sum << endl;
  }
  return 0;
}
