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.io.*;
import java.math.*;
import java.util.*;

public class Main {

    static final int MAX_N = 1000010;
    static final int INF = 0x3f3f3f3f;
    static final int mod = 1000000007;


    public static void main(String[] args) throws IOException {
        initReader(System.in);


        int T = nextInt();
        for (int i = 1; i <= T; i++)
        solve();


        pw.flush();
    }


    /*******************************************************************************************************************************/


    public static void solve() throws IOException {
        int n = nextInt();
        char[] s = next().toCharArray();
        char[] ss = new char[n];

        System.arraycopy(s, 0, ss, 0, n);

        Arrays.sort(s);

        int ans = 0;
        for (int i = 0; i < n; i++) if (s[i] != ss[i]) ans++;
        pw.println(ans);
    }

    static class Pair {
        char x;
        int y;

        Pair (char x, int y) {
            this.x = x;
            this.y = y;
        }
    }

    /*******************************************************************************************************************************/


    /*******************************************************************************************************************************/

    static BufferedReader reader;
    static StringTokenizer tokenizer;
    static PrintWriter pw;

    public static void initReader(InputStream input) throws IOException {
        reader = new BufferedReader(new InputStreamReader(input));
        tokenizer = new StringTokenizer("");
        pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));

//        reader = new BufferedReader(new FileReader("test.in"));
//        tokenizer = new StringTokenizer("");
//        pw = new PrintWriter(new BufferedWriter(new FileWriter("test1.out")));
    }

    public static boolean hasNext() {
        try {
            while (!tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(reader.readLine());
            }
        } catch (Exception e) {
            return false;
        }
        return true;
    }

    public static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    public static String nextLine() {
        try {
            return reader.readLine();
        } catch (Exception e) {
            return null;
        }
    }

    public static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    public static long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    public static double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    public static char nextChar() throws IOException {
        return next().charAt(0);
    }

    public static short nextShort() throws IOException {
        return Short.parseShort(next());
    }

}

