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").
//package Codeforces.GR15;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class A {

    static final long mod = (long) 1e9 + 7l;

    private static void solve(int t) {
        int n = fs.nextInt();
        char[] chr = fs.next().toCharArray();
        char[] sorted = new char[n];
        for (int i = 0; i < n; i++) {
            sorted[i] = chr[i];
        }
        Arrays.sort(sorted);
        int k = 0;
        for (int i = 0; i < n; i++) {
            if (chr[i] != sorted[i]) k++;
        }
        System.out.println(k);
    }

    static class pair {
        int a;
        int b;

        public pair(int a, int b) {
            this.a = a;
            this.b = b;
        }

        @Override
        public String toString() {
            return "pair{" +
                    "a=" + a +
                    ", b=" + b +
                    '}';
        }
    }

    public static void main(String[] args) {
        fs = new FastScanner();
        out = new PrintWriter(System.out);
        long s = System.currentTimeMillis();
        int t = fs.nextInt();
        for (int i = 1; i <= t; i++) solve(t);
        out.close();
//        System.err.println( System.currentTimeMillis() - s + "ms" );
    }

    static boolean DEBUG = true;
    static PrintWriter out;
    static FastScanner fs;

    static void trace(Object... o) {
        if (!DEBUG) return;
        System.err.println(Arrays.deepToString(o));
    }

    static void pl(Object o) {
        out.println(o);
    }

    static void p(Object o) {
        out.print(o);
    }

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

    static int gcd(int a, int b) {
        return (b == 0) ? a : gcd(b, a % b);
    }

    static void sieveOfEratosthenes(int n, int factors[]) {
        factors[1] = 1;
        for (int p = 2; p * p <= n; p++) {
            if (factors[p] == 0) {
                factors[p] = p;
                for (int i = p * p; i <= n; i += p)
                    factors[i] = p;
            }
        }
    }

    static long mul(long a, long b) {
        return a * b % mod;
    }

    static long fact(int x) {
        long ans = 1;
        for (int i = 2; i <= x; i++) ans = mul(ans, i);
        return ans;
    }

    static long fastPow(long base, long exp) {
        if (exp == 0) return 1;
        long half = fastPow(base, exp / 2);
        if (exp % 2 == 0) return mul(half, half);
        return mul(half, mul(half, base));
    }

    static long modInv(long x) {
        return fastPow(x, mod - 2);
    }

    static long nCk(int n, int k) {
        return mul(fact(n), mul(modInv(fact(k)), modInv(fact(n - k))));
    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        public String next() {
            while (!st.hasMoreElements())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

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

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }

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