write a go solution for Description:
You are given two strings s and t of equal length n. In one move, you can swap any two adjacent characters of the string s.

You need to find the minimal number of operations you need to make string s lexicographically smaller than string t.

A string a is lexicographically smaller than a string b if and only if one of the following holds:

- a is a prefix of b, but aneb;
- in the first position where a and b differ, the string a has a letter that appears earlier in the alphabet than the corresponding letter in b.

Input Format:
The first line of input contains one integer q (1<=q<=10,000): the number of test cases.

The first line of each test case contains a single integer n (1<=n<=10^5).

The second line of each test case contains the string s consisting of n lowercase English letters.

The third line of each test case contains the string t consisting of n lowercase English letters.

It is guaranteed that the sum of n over all test cases does not exceed 2*10^5.

Output Format:
For each test case, print in a separate line the minimal number of operations you need to make string s lexicographically smaller than string t, or -1, if it's impossible.

Note:
None. Output only the code with no comments, explanation, or additional text.