A. Subsequence Permutationtime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputA string s of length n, consisting of lowercase letters of the English alphabet, is given.You must choose some number k between 0 and n. Then, you select k characters of s and permute them however you want. In this process, the positions of the other n-k characters remain unchanged. You have to perform this operation exactly once.For example, if s=\texttt{"andrea"}, you can choose the k=4 characters \texttt{"a_d_ea"} and permute them into \texttt{"d_e_aa"} so that after the operation the string becomes \texttt{"dneraa"}.Determine the minimum k so that it is possible to sort s alphabetically (that is, after the operation its characters appear in alphabetical order).InputThe first line contains a single integer t (1 \le t \le 1000) — the number of test cases. Then t test cases follow.The first line of each test case contains one integer n (1 \le n \le 40) — the length of the string.The second line of each test case contains the string s. It is guaranteed that s contains only lowercase letters of the English alphabet.OutputFor each test case, output the minimum k that allows you to obtain a string sorted alphabetically, through the operation described above.ExampleInput
4
3
lol
10
codeforces
5
aaaaa
4
dcba
Output
2
6
0
4
NoteIn the first test case, we can choose the k=2 characters \texttt{"_ol"} and rearrange them as \texttt{"_lo"} (so the resulting string is \texttt{"llo"}). It is not possible to sort the string choosing strictly less than 2 characters.In the second test case, one possible way to sort s is to consider the k=6 characters \texttt{"_o__force_"} and rearrange them as \texttt{"_c__efoor_"} (so the resulting string is \texttt{"ccdeefoors"}). One can show that it is not possible to sort the string choosing strictly less than 6 characters.In the third test case, string s is already sorted (so we can choose k=0 characters).In the fourth test case, we can choose all k=4 characters \texttt{"dcba"} and reverse the whole string (so the resulting string is \texttt{"abcd"}).
4
3
lol
10
codeforces
5
aaaaa
4
dcba

2 6 0 4 
['sortings', 'strings', '*800']