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").
//---#ON_MY_WAY---
import static java.lang.Math.*;
import java.io.*;
import java.math.*;
import java.util.*;

public class A {
	static FastReader  x= new FastReader();
	static OutputStream outputStream = System.out;
	static PrintWriter out = new PrintWriter(outputStream);

	/*---------------------------------------CODE STARTS HERE-------------------------*/
	public static void main(String[] args) {

		int t = x.nextInt();
		StringBuilder str = new StringBuilder();
		while (t > 0) {
			int n=x.nextInt();
			String s=x.next();
			char a[]=s.toCharArray();
			int c=0;
			Arrays.sort(a);
			for (int i = 0; i < n; i++) {
				if(s.charAt(i)!=a[i]) {
					c++;
				}
			}
			str.append(c);
			str.append("\n");
			t--;
		}
		out.println(str);
		out.flush();
	}

	/*--------------------------------------------FAST I/O--------------------------------*/
	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;
		}

		char nextchar() {
			char ch = ' ';
			try {
				ch = (char) br.read();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return ch;
		}
	}

	/*--------------------------------------------BOILER PLATE---------------------------*/
	static int[] readarr(int n) {
		int arr[] = new int[n];
		for (int i = 0; i < n; i++) {
			arr[i] = x.nextInt();
		}
		return arr;
	}

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

	static int[] revsort(int a[]) {
		ArrayList<Integer> al = new ArrayList<>();
		for (int i : a) {
			al.add(i);
		}
		Collections.sort(al, Comparator.reverseOrder());
		for (int i = 0; i < a.length; i++) {
			a[i] = al.get(i);
		}
		return a;
	}

	static int[] gcd(int a, int b, int ar[]) {
		if (b == 0) {
			ar[0] = a;
			ar[1] = 1;
			ar[2] = 0;
			return ar;
		}
		ar = gcd(b, a % b, ar);
		int t = ar[1];
		ar[1] = ar[2];
		ar[2] = t - (a / b) * ar[2];
		return ar;
	}

	static boolean[] esieve(int n) {
		boolean p[] = new boolean[n + 1];
		Arrays.fill(p, true);
		for (int i = 2; i * i <= n; i++) {
			if (p[i] == true) {
				for (int j = i * i; j <= n; j += i) {
					p[j] = false;
				}
			}
		}
		return p;
	}

	static ArrayList<Integer> primes(int n) {
		boolean p[] = new boolean[n + 1];
		ArrayList<Integer> al = new ArrayList<>();
		Arrays.fill(p, true);
		int i = 0;
		for (i = 2; i * i <= n; i++) {
			if (p[i] == true) {
				al.add(i);
				for (int j = i * i; j <= n; j += i) {
					p[j] = false;
				}
			}
		}
		for (i = i; i <= n; i++) {
			if (p[i] == true) {
				al.add(i);
			}
		}
		return al;
	}

	static int etf(int n) {
		int res = n;
		for (int i = 2; i * i <= n; i++) {
			if (n % i == 0) {
				res /= i;
				res *= (i - 1);
				while (n % i == 0) {
					n /= i;
				}
			}
		}
		if (n > 1) {
			res /= n;
			res *= (n - 1);
		}
		return res;
	}
}