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

public class A_Subsequence_Permutation {
    public static void main (String[] args) {
        FastReader scan = new FastReader();
        int t = scan.nextInt();
        while (t-- > 0) {
            int n = scan.nextInt();
            String str = scan.nextLine();
            char[] arr = str.toCharArray();
            Arrays.sort(arr);
            String str1 = new String(arr);
            int count = 0;
            for (int i=0; i<n; i++) {
                if (str.charAt(i) != str1.charAt(i)) {
                    count++;
                }
            }
            System.out.println(count);
        }
    }
    public static void inputArray (int[] arr, int n, FastReader scan) {
        for (int i=0; i<n; i++) {
            arr[i] = scan.nextInt();
        }
    }
    public static void printArray (int[] arr) {
        for (int i=0; i<arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }
    public static boolean isPrime (int n) {
        if (n <= 1)
            return false;
        if (n <= 3)
            return true;
        if (n % 2 == 0 || n % 3 == 0)
            return false;
        for (int i = 5; i * i <= n; i = i + 6)
            if (n % i == 0 || n % (i + 2) == 0)
                return false;
        return true;
    }
    public static int gcd (int a, int b) {
        BigInteger a1 = BigInteger.valueOf(a);
        BigInteger b1 = BigInteger.valueOf(b);
        return a1.gcd(b1).intValue();
    }
    public static int numberOfDigitsInNumber (int n) {
        return (int)Math.floor(Math.log10(n)) + 1;
    }
    public static boolean isPowerOfTwo (int x) {
        return x!=0 && ((x&(x-1)) == 0);   
    }
    public static String toBinaryString (int n) {
        return Integer.toString(n, 2);
        // for other bases change 2 to other bases
    }
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;
 
        public FastReader()
        {
            br = new BufferedReader(
                new InputStreamReader(System.in));
        }
 
        String next()
        {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
 
        int nextInt() { return Integer.parseInt(next()); }
 
        long nextLong() { return Long.parseLong(next()); }
 
        double nextDouble()
        {
            return Double.parseDouble(next());
        }
 
        String nextLine()
        {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}

// For IO using Files
// public static void main throws IOException
// BufferedReader br = new BufferedReader(new FileReader("input.txt"));
// PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("output.txt")));
// String st[]=br.readLine().split(" ");
// int n=Integer.parseInt(st[0]);
// int m=Integer.parseInt(st[1]);
// at the end
// br.close(); pw.close();
// for printing pw.println(), pw.print(), etc...
// for arrays : int arr[] = Arrays.stream(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();