카잉 달력

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class BOJ_6064 {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int t = Integer.parseInt(br.readLine());
        while (t-- > 0) {
            String[] line = br.readLine().split("\\s");
            int m = Integer.parseInt(line[0]);
            int n = Integer.parseInt(line[1]);
            int x = Integer.parseInt(line[2]);
            int y = Integer.parseInt(line[3]);

            int tempX = x;
            int tempY = x;
            boolean ok = false;

            while (tempY <= m * n) {

                // 1. y != n
                // 2. y == n
                if ((tempY % n) == y || (tempY % n) == 0 && y % n == 0) {
                    System.out.println(tempY);
                    ok = true;
                    break;
                }


                tempY += m;
            }
            if (!ok)
                System.out.println(-1);
        }
    }
}