Please subscribe to the official Codeforces channel in Telegram via the link https://t.me/codeforces_official. ×

A. Subsequence Permutation
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

A 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).

Input

The 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.

Output

For each test case, output the minimum $$$k$$$ that allows you to obtain a string sorted alphabetically, through the operation described above.

Example
Input
4
3
lol
10
codeforces
5
aaaaa
4
dcba
Output
2
6
0
4
Note

In 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 $$$\texttt{"abcd"}$$$).