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.sql.Array;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.Instant;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class Main {
    public static class Node implements Comparable<Node> {
        int my;
        int oth;
        Node(int my,int oth) {
            this.my = my;
            this.oth = oth;
        }

        @Override
        public int compareTo(Node o) {
            return ((o.oth - o.my) - (this.oth - this.my));
        }
    }

    public static class Point implements Comparable<Point>{
        int i;
        int j;
        Point(int i, int j) {
            this.i = i;
            this.j = j;
        }

        @Override
        public int compareTo(Point o) {
            return this.i - o.i;
        }
    }

    static long inverse(int n,int MD) {
        return n == 1 ? 1 : inverse(n - MD % n, MD) * (MD / n + 1) % MD;
    }

    static long choose(int n, int k, int MD) {
        return k == 0 ? 1 : choose(n - 1, k - 1, MD) * n % MD * inverse(k, MD) % MD;
    }

    /************************ SOLUTION STARTS HERE ************************/
    private static void solve() {
        int t = nextInt();

        while(t-- > 0) {
            int n = nextInt();
            String s = nextLine();
            String[] orig = s.split("");
            String[] arr = s.split("");
            Arrays.sort(arr);

            int cnt = 0;
            for(int i=0;i<n;i++)
                if(!arr[i].equals(orig[i])) cnt++;

            println(cnt);
        }
    }


    /************************ SOLUTION ENDS HERE ************************/



    /************************ TEMPLATE STARTS HERE **********************/

    public static void main(String[] args) throws IOException, ParseException {
        reader = new BufferedReader(new InputStreamReader(System.in));
        writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)), false);
        st = null;
        solve();
        reader.close();
        writer.close();
    }

    static BufferedReader  reader;
    static PrintWriter     writer;
    static StringTokenizer st;

    static String next() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                String line = reader.readLine();
                if (line == null) {
                    return null;
                }
                st = new StringTokenizer(line);
            } catch (Exception e) {
                throw new RuntimeException();
            }
        }
        return st.nextToken();
    }

    static String nextLine() {
        String s = null;
        try {
            s = reader.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return s;
    }

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

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

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

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

    static int[] nextIntArray(int n) {
        int[] a = new int[n];
        int i = 0;
        while (i < n) {
            a[i++] = nextInt();
        }
        return a;
    }

    static long[] nextLongArray(int n) {
        long[] a = new long[n];
        int i = 0;
        while (i < n) {
            a[i++] = nextLong();
        }
        return a;
    }

    static int[] nextIntArrayOneBased(int n) {
        int[] a = new int[n + 1];
        int i = 1;
        while (i <= n) {
            a[i++] = nextInt();
        }
        return a;
    }

    static long[] nextLongArrayOneBased(int n) {
        long[] a = new long[n + 1];
        int i = 1;
        while (i <= n) {
            a[i++] = nextLong();
        }
        return a;
    }

    static void print(Object o) {
        writer.print(o);
    }

    static void println(Object o) {
        writer.println(o);
    }

    static void printArr(int[] arr) {
        for(int i = 0 ; i < arr.length; i++)
            System.out.print(arr[i] + " ");
        System.out.println();
    }

    public static void exchange(int[] arr, int i, int j) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }

    public static void shuffle(int arr[], int n) {
        for (int i = 0; i < n; i++) {
            int r = (int)Math.floor(Math.random() * (i+1));
            exchange(arr, i, r);
        }
    }

    /************************ TEMPLATE ENDS HERE ************************/
}
