#include <bits/stdc++.h>
using namespace std;
const long long N = 200005, INF = 2000000000000000000;
long double pi = 3.1415926535897932;
long long powere(long long a, long long b, long long p) {
  if (a == 0) return 0;
  long long res = 1;
  a %= p;
  while (b > 0) {
    if (b & 1) res = (res * a) % p;
    b >>= 1;
    a = (a * a) % p;
  }
  return res;
}
void copy(long long a[2][2], long long b[2][2]) {
  for (long long i = 0; i < 2; i++) {
    for (long long j = 0; j < 2; j++) b[i][j] = a[i][j];
  }
}
void matmult(long long m1[2][2], long long m2[2][2], long long m3[2][2]) {
  for (long long i = 0; i < 2; i++) {
    for (long long j = 0; j < 2; j++) {
      m3[i][j] = 0;
      for (long long k = 0; k < 2; k++) {
        m3[i][j] +=
            (m1[i][k] % 1000000007 * m2[k][j] % 1000000007) % 1000000007;
        m3[i][j] %= 1000000007;
      }
    }
  }
}
void power(long long mat[2][2], long long b, long long p,
           long long finres[2][2]) {
  long long res[2][2] = {{0}}, cc[2][2];
  res[0][0] = res[1][1] = 1;
  while (b > 0) {
    copy(res, cc);
    if (b & 1) matmult(mat, cc, res);
    copy(mat, cc);
    b >>= 1;
    matmult(cc, cc, mat);
  }
  copy(res, finres);
}
int32_t main() {
  std::ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cout.precision(std::numeric_limits<double>::max_digits10);
  ;
  long long t;
  cin >> t;
  while (t--) {
    long long x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    long long x = abs(x1 - x2), y = abs(y1 - y2);
    if (y < x) swap(x, y);
    long long ans = (x * (x + 1));
    ans += ((y - x - 1) * x);
    cout << ans + 1 << "\n";
  }
}
