## 题目描述

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).

## 输入格式

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.

## 输出格式

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

## 输入输出样例

### 输入 #1

4
3
lol
10
codeforces
5
aaaaa
4
dcba

### 输出 #1

2
6
0
4

## 代码

#include<bits/stdc++.h>
using namespace std;
int t,n;
char a[51];
int c[51],b[51];
int main(){
scanf("%d",&t);
while(t--){
scanf("%d",&n);
for(int i=1;i<=n;i++)cin>>a[i],c[i]=a[i]-96,b[i]=c[i];
int ans=0;
sort(b+1,b+1+n);
for(int i=1;i<=n;i++)if(c[i]!=b[i])ans++;
printf("%d\n",ans);
}
}