//6064 카잉 달력
#include <iostream>
using namespace std;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int t;
int m, n, x, y;
cin >> t;
int day = 0;
while (t--) {
day = -1;
cin >> m >> n >> x >> y;
if (x == m)
x = 0;
if (y == n)
y = 0;
for (int i = x; i <= m * n; i+=m) {
if (i % n == y)){
day = i;
break;
}
}
cout << day << "\n";
}
}