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.util.Scanner;

public class Nfdssjf {

	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);
		int n = scn.nextInt();
		int arr[] = new int[n];
		String arrs[] = new String[n];
		for (int i = 0; i < n; i++) {
			arr[i] = scn.nextInt();
			arrs[i] = scn.next();
		}
		for (int i = 0; i < n; i++) {
			System.out.println(sortArray(arr[i], arrs[i]));
		}
		
	}

	private static int sortArray(int i, String s) {
		try {
			if(i > s.length() || i < s.length()) return 0;
			
			char c[] = s.toCharArray();
			
			int[] arr = new int[26];
			
			for (int j = 0; j < arr.length; j++) {
				arr[j] = 0;
			}
			
			int a = 0;
			for (int j = 0; j < c.length; j++) {
				a = c[j]-'a';
				arr[c[j]-'a']++;
			}
			
			char c1[] = new char[s.length()];
			int l = 0;
			for (int j = 0; j < arr.length; j++) {
				if(arr[j] != 0)
					for (int j2 = 0; j2 < arr[j]; j2++) {
						c1[l] = (char)(j+97);
						l++;
					}
			}
			
			int count = 0;
			for (int j = 0; j < c.length; j++) {
				if(c[j] == c1[j]) {
					count++;
				}
			}

			
			return c.length-count;
		} catch (Exception e) {
			return 0;
		}
		
	}

}
