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.lang.*;
import java.io.*;

//author: ankit_bit

public class Main {

    static FastReader fr = new FastReader();
    static StringBuilder sb = new StringBuilder();

    public static void main(String[] args) throws java.lang.Exception {

        int testcases = fr.nextInt();
        while (testcases-- > 0) {

            solve();
        }
        System.out.println(sb);

    }

    public static void solve() {
        int n=fr.nextInt();
        String s=fr.nextLine();
        int count=0;
        char c[]=s.toCharArray();
        Arrays.sort(c);
        for(int i=0;i<n;i++)
        {
            if(s.charAt(i)!=c[i])
                count++;
        }
        sb.append(count);
        sb.append("\n");
    }



    static boolean isPrime(int x) {
        for (int d = 2; d * d <= x; d++) {
            if (x % d == 0)
                return false;
        }
        return true;
    }

    static int lowerBound(int a[], int low, int high, int x) {
        int pos = -1;
        while (low <= high) {
            int mid = (low + high) / 2;
            if (a[mid] == x) {
                pos = mid;
                high = mid - 1;
            } else if (a[mid] < x) low = mid + 1;
            else high = mid - 1;
        }
        if (pos != -1) return pos;
        return high + 1;
    }

    static int upperBound(int a[], int low, int high, int x) {
        int pos = -1;
        while (low <= high) {
            int mid = (low + high) / 2;
            if (a[mid] == x) {
                pos = mid;
                low = mid + 1;
            } else if (a[mid] < x) low = mid + 1;
            else high = mid - 1;
        }
        if (pos != -1) return pos;
        return high + 1;
    }

    static long mult(long a, long b, long mod) {
        long res = (a * b) % mod;
        if (res < 0) {
            res += mod;
        }
        return res;
    }

    static long add(long a, long b, long mod) {
        long res = (a + b) % mod;
        if (res < 0) {
            res += mod;
        }
        return res;
    }

    static long gcd(long a, long b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

    static long lcm(long a, long b) {
        return (a / gcd(a, b)) * b;
    }

    static long fact[] = new long[100001], M = 1000000007;

    static long ncr(int n, int r) {
        if (r > n) return 0;
        return fact[n] * power(fact[r], M - 2) % M * power(fact[n - r], M - 2) % M;
    }

    static long power(long a, long b) {
        long res = 1;
        while (b != 0) {
            if (b % 2 == 1) res = res * a % M;
            b >>= 1;
            a = a * a % M;
        }
        return res;
    }


    static void sort(int[] a) {
        ArrayList<Integer> l = new ArrayList<>();
        for (int i = 0; i < a.length; i++) {
            l.add(a[i]);
        }
        Collections.sort(l);
        for (int i = 0; i < l.size(); i++)
            a[i] = l.get(i);
    }

}

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;
    }
}
