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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.*;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

public class java1 {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskB solver = new TaskB();
        solver.solve(1, in, out);
        out.close();
    }
    static class TaskB {

        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int t=in.nextInt();
          tt:  while(t-- >0)
            {
            	int n=in.nextInt();
            	String s=in.next();
            	char ch[]=s.toCharArray();
            	
            	Arrays.parallelSort(ch);
            	
            	int count=0;
            	for(int x=0;x<n;x++)
            	{
            		//out.println(ch1[x]);
            		if(ch[x]!=s.charAt(x)) {
            			count++;
            		}
            	}
            	out.println(count);
            	
            	
            }
        }
        static void sort(int[] a) {
    		ArrayList<Integer> l=new ArrayList<>();
    		for (int i:a) l.add(i);
    		Collections.sort(l);
    		for (int i=0; i<a.length; i++) a[i]=l.get(i);
    	}
        
    }
    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }
        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
        public int nextInt() {
            return Integer.parseInt(next());
        }
        public long nextLong() {
            return Long.parseLong(next());
        }
        public int[] inputarInt(int n)
        {
        	int ar[]=new int[n];
        	for(int x=0;x<n;x++)
        	{
        		ar[x]=nextInt();
        	}
        	return ar;
        }
        public long[] inputarLong(int n)
        {
        	long ar[]=new long[n];
        	for(int x=0;x<n;x++)
        	{
        		ar[x]=nextLong();
        	}
        	return ar;
        }
        
    }
}