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="andrea", you can choose the k=4 characters "a_d_ea" and permute them into "d_e_aa" so that after the operation the string becomes "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 ≤ t ≤ 1000) — the number of test cases. Then t test cases follow.

The first line of each test case contains one integer n (1 ≤ n ≤ 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 "_ol" and rearrange them as "_lo" (so the resulting string is "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 "_o__force_" and rearrange them as "_c__efoor_" (so the resulting string is "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 "dcba" and reverse the whole string (so the resulting string is "abcd").
import java.util.*;
import java.io.*;
import java.math.*;
import java.math.BigInteger;
/**
 *
 * @author alanl
 */
public class Main{
    static BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st;
    static PrintWriter pr = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    static Integer[][]arr;
    static int ans = -1;
    public static void main(String[] args) throws IOException {
        int t = readInt();
        while(t-->0){
            int n = readInt();
            String s = readLine();
            char[]arr = s.toCharArray();
            Arrays.sort(arr);
            int ans = 0;
            for(int i = 0; i<n; i++){
                if(arr[i]!=s.charAt(i))ans++;
            }
            println(ans);
        }
    }
    static String next () throws IOException {
        while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(input.readLine().trim());
        return st.nextToken();
    }
    static long readLong () throws IOException {
        return Long.parseLong(next());
    }
    static int readInt () throws IOException {
        return Integer.parseInt(next());
    }
    static double readDouble () throws IOException {
        return Double.parseDouble(next());
    }
    static char readChar () throws IOException {
        return next().charAt(0);
    }
    static String readLine () throws IOException {
        return input.readLine().trim();
    }
    static void print(Object b) {
        System.out.print(b);
    }
    static void println(Object b) {
        System.out.println(b);
    }
    static void println() {
        System.out.println();
    }
}
