#include <bits/stdc++.h>
using namespace std;
int main() {
  int test;
  cin >> test;
  while (test--) {
    long long x1, x2, y1, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    cout << (long long)((x2 - x1) * (y2 - y1)) + 1 << "\n";
  }
}
