#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
    int k;
    cin >> k;
    vector <int> matrix;
    vector <int> area;
    int d, s, s1, s2;
    string l;
    for (int i = 0; i < k; ++i) {
        for (int j = 0; j < 4; ++j) {
            cin >> d;
            matrix.push_back(d);
        }
    }

    for (int i = 0; i < k; ++i) {
        for (int j = 0; j < 1; ++j) {
            if (matrix[2] == 0 && matrix[3] == 0) {
                s = (matrix[0] - 1) * matrix[1];
                area.push_back(s);
                break;
            }
            if (matrix[2] == matrix[0] && matrix[3] == 0) {
                s = (matrix[0] - 1) * matrix[1];
                area.push_back(s);
                break;
            }
            if (matrix[2] == 0 && matrix[3] == matrix[1]) {
                s = (matrix[1] - 1) * matrix[0];
                area.push_back(s);
                break;
            }
            if (matrix[2] == matrix[0] && matrix[3] == matrix[1]) {
                s = (matrix[1] - 1) * matrix[0];
                area.push_back(s);
                break;
            }

            s1 = matrix[0] - matrix[2] * mat;



        }
    }
    return 0;
}