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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
public class vamsi
{ 
	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; 
		} 
    }
    static FastReader s = new FastReader();
    static StringBuilder sb = new StringBuilder();
	public static void main(String[] args) 
	{ 
		int t=s.nextInt();
		while(t-->0)
		{
		    int n=s.nextInt(),count=0;
		    String st=s.next();
		    char c[] = st.toCharArray();
		    Arrays.sort(c);
		    for(int i=0;i<n;i++)
		    {
		        if(c[i]!=st.charAt(i))
		        count++;
		    }
		    sb.append(count);
		    sb.append("\n");
		}
		System.out.print(sb);
    }
}
