Dramatic Multiplications

Hassan, helping with his younger brother's homework, found out that when you multiply 102564 by 4, its right-most digit moves to the left, and the other digits move one position to the right; i.e. 4 * 102564 = 410256. We call a number that has this property when multiplied by n, an n-dramatic number. For instance, 102564 and 128205 are both 4-dramatic. Given two one-digit numbers n and k, the goal is to find the smallest n-dramatic number that its rightmost digit is k.

On the first line of the input, there is an integer t, which is the number of cases that follow. Each test case, is on a line by itself, and contains two integers n and k, where 1 <= n <= 9, and 1 <= k <= 9.

For each test case, output a single integer on a line by itself, which is the smallest n-dramatic number that its rightmost digit is k. If no such number exists, output 0 instead.

2
4 5
2 1

128205
0