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.* ;
import java.util.* ;


 
public class App {
    public static void main (String[] args) throws java.lang.Exception {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        //reader = new BufferedReader(new FileReader(new File("C:\\Users\\Anjali\\Desktop\\projects\\HelloWorld\\src\\input.txt")));
		BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
        //writer = new BufferedWriter(new FileWriter(new File("C:\\Users\\Anjali\\Desktop\\projects\\HelloWorld\\src\\output.txt")));
		//int tests = Integer.parseInt(reader.readLine());
        int tests = 1;
		//StringBuilder sb = new StringBuilder(tests);
		while (tests-- > 0){
		    solve(reader, writer);
            writer.write("\n");
		}
		reader.close();
        writer.flush();
        writer.close();
    }

 
    static void solve(BufferedReader reader, BufferedWriter writer) throws  IOException {
		int tests = Integer.parseInt(reader.readLine());
		for (int i = 0; i < tests; i++) {
			int n = Integer.parseInt(reader.readLine());
			String s = reader.readLine();
			String s1 = s;
			char[] a = s.toCharArray();
			char[] a1 = s1.toCharArray();
			Arrays.sort(a);
			int count = 0;
			for (int j = 0; j < n; j++) {
				if (a[j] != a1[j]) {
					count++;
				}
			}
			writer.write(count + "\n");
		}	
	}
}
