Minimum Operations to Make Strings Equal

Given two strings A and B consisting of lowercase English letters, determine the minimum number of pre-processing moves required on string A to make it equal to string B using the following operations:

1. Choose any index i (0 <= i < n) and swap characters a[i] and b[i]. 2. Choose any index i (0 <= i < n) and swap characters a[i] and a[n-i-1]. 3. Choose any index i (0 <= i < n) and swap characters b[i] and b[n-i-1].

In one pre-process move, you can replace a character in A with any other character of the English alphabet.

Note:

1. The number of changes you make after the pre-process move does not matter. 2. You cannot apply pre-process moves to the string B or make any pre-process moves after the first change is made.

Input:

The first line of input contains an integer ‘T’ representing the number of test cases. Then the test cases follow. The first line of each test case contains string A consisting of lowercase English letters. The second line of each test case contains string B consisting of lowercase English letters.

Output:

For each test case, print a single integer denoting the minimum number of pre-processing moves on the string A required to make it equal to the string B. Print -1, if it is impossible to make strings equal. The output for each test case is in a separate line.

Constraints:

• 1 <= T <= 100
• 1 <= N <= 5000
• Where N is the length of the strings.
• Time Limit: 1 sec