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#include <iostream>
#include <algorithm>
using namespace std;

int main() {
	// your code goes here
	int t; cin>>t;
	while (t--) {
	    long n, m, x, y;
	    cin>>n>>m>>x>>y;
	    cout << max ({(y-1)*n, (x-1)*m, (m-y)*n, (n-x)*m}) << "\n";
	}
	return 0;
}