#include <bits/stdc++.h>
using namespace std;
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
void read(vector<long long> &v) {
  for (auto &i : v) cin >> i;
}
const long long INF = 1e9;
const int64_t INFF = 1e18;
const long long N = 1e7 + 69;
void solve() {
  long long x1, x2, y1, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  cout << (x2 - x1) * (y2 - y1) + 1 << "\n";
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long t = 1;
  cin >> t;
  for (long long i = 1; i <= t; i++) {
    solve();
  }
  return 0;
}
