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;

public class Solution {
	
	public static void merge(char[] a, int l, int m, int r) {
		int n1 = m-l+1;
		int n2 = r-m;
		
		char[] left = new char[n1];
		char[] right = new char[n2];
		
		for(int i = 0; i<n1; i++) {
			left[i] = a[i+l];
		}
		for(int j = 0; j<n2; j++) {
			right[j] = a[m+j+1];
		}
		
		int i = 0; int j = 0;
		int k = l;
		while(i<n1 && j<n2) {
			if(left[i] < right[j]) {
				a[k] = left[i];
				i++;
				k++;
			}
			else {
				a[k] = right[j];
				j++;
				k++;
			}
		}
		while(i<n1) {
			a[k] = left[i];
			i++;
			k++;
		}
		while(j<n2) {
			a[k] = right[j];
			j++;
			k++;
		}
		
	}
	
	public static void sort(char[] sarr, int l, int r) {
		if(l<r) {
			int m = (l+r)/2;
			sort(sarr, l, m);
			sort(sarr, m+1, r);
			merge(sarr, l, m, r);
		}
	}

	public static void main(String[] args) throws IOException{
		// TODO Auto-generated method stub
		BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
		int t = Integer.parseInt(read.readLine().split(" ")[0]);
		for(int i = 0; i<t; i++) {
			int n = Integer.parseInt(read.readLine().split(" ")[0]);
			String s = read.readLine();	
			char[] sarr = s.toCharArray();
			sort(sarr, 0, n-1);
			int ans = 0;
			for(int j = 0; j<n; j++) {
				if(s.charAt(j)==sarr[j]) {
					ans++;
				}
			}
			ans = n-ans;
			System.out.println(ans);
		}
	}

}