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