#include <bits/stdc++.h>
const long base = 151;
const long long MM = 1ll * 1000000007 * 1000000007;
using namespace std;
int BIT(int i, long long x) { return (x & (1 << i)); }
long long ONBIT(int i, long long x) { return (x | (1 << i)); }
long long OFFBIT(int i, long long x) { return (x & ~(1 << i)); }
long long FLIPBIT(int i, long long x) { return (x ^ (1 << i)); }
long long NUMBIT(long long x) { return __builtin_popcount(x); }
template <class T>
T GCD(T a, T b) {
  T r;
  while (b != 0) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
template <class T>
T LCM(T a, T b) {
  return a / GCD(a, b) * b;
}
void read() {
  int x, y, u, v;
  long long ans = 1;
  cin >> x >> y >> u >> v;
  int s1 = u - x;
  int s2 = v - y;
  long long tmp = min(s1, s2) - 1;
  ans += (tmp + 1) * (abs(s2 - s1) + 1);
  ans += (tmp + 1) * tmp;
  cout << ans << endl;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  long te;
  cin >> te;
  while (te--) read();
}
