You are given two non-empty strings X and Y of same length n. Your task is to make them identical. But the problem is that the only operation you can do is flipping, and it can only be applied to X.

For a flip, two positions of the string X are chosen, let the positions be i and j (0 ≤ i < j < n) and if you apply flip (i, j) all characters between i and j (inclusive) are reversed. For example, let X be "abcdefg", then if you apply flip (2, 5) to X then X will be "abfedcg". But if you want to apply flips more than once, you have to use ordered flips. If flip (i₂, j₂) is applied immediately after flip (i₁, j₁), then it will be said "Ordered Flips" if and only if i₁ ≤ i₂ and j₂ ≤ j₁.

So, now your task is to find the minimum number of ordered flips to change X to Y.

Input starts with an integer T (≤ 200), denoting the number of test cases.

Each case contains two lines, each containing a non empty string of length n (1 ≤ n ≤ 60). The strings contain lowercase English letters only. First line contains X and second line contains Y.

For each case, print the case number and the minimum number of ordered flips needed to change X to Y. If it's impossible to do so, then print impossible. Check the samples for details.