CF773A.Success Rate

You are an experienced Codeforces user. Today you found out that during your activity on Codeforces you have made $y$ submissions, out of which $x$ have been successful. Thus, your current success rate on Codeforces is equal to $x/y$ .

Your favorite rational number in the $[0;1]$ range is $p/q$ . Now you wonder: what is the smallest number of submissions you have to make if you want your success rate to be $p/q$ ?

The first line contains a single integer $t$ ( $1<=t<=1000$ ) — the number of test cases.

Each of the next $t$ lines contains four integers $x$ , $y$ , $p$ and $q$ ( $0<=x<=y<=10^{9}$ ; $0<=p<=q<=10^{9}$ ; $y>0$ ; $q>0$ ).

It is guaranteed that $p/q$ is an irreducible fraction.

Hacks. For hacks, an additional constraint of $t<=5$ must be met.

For each test case, output a single integer equal to the smallest number of submissions you have to make if you want your success rate to be equal to your favorite rational number, or -1 if this is impossible to achieve.

In the first example, you have to make 4 successful submissions. Your success rate will be equal to $7/14$ , or $1/2$ .

In the second example, you have to make 2 successful and 8 unsuccessful submissions. Your success rate will be equal to $9/24$ , or $3/8$ .

In the third example, there is no need to make any new submissions. Your success rate is already equal to $20/70$ , or $2/7$ .

In the fourth example, the only unsuccessful submission breaks your hopes of having the success rate equal to 1.