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 seqPermute {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(
                new InputStreamReader(System.in));
        }
        public FastReader(String file_name)throws IOException
        {
            br = new BufferedReader(
                new FileReader(file_name));
        }

        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;
        }
        
        public int[] nextArray(int n){
            int ar[] = new int[n];
            for(int i=0;i<n;i++)
                ar[i] = this.nextInt();
            return (ar);
        }
    }

   static class OutputWriter{
        BufferedWriter writer;

         public OutputWriter(OutputStream stream){
           writer = new BufferedWriter(new OutputStreamWriter(stream));
         }

         public OutputWriter(String file_name) throws IOException{
           writer = new BufferedWriter(new FileWriter("output.txt"));
         }
       
         public void print(int i) throws IOException {
           writer.write(i);
         }

         public void print(String s) throws IOException {
            writer.write(s);
          }

         public void print(char []c) throws IOException {
            writer.write(c);
         }

         public void println(int i) throws IOException {
           writer.write(i+"\n");
         }

         public void println(long i) throws IOException {
           writer.write(i+"\n");
         }

         public void println(String s) throws IOException {
            writer.write(s+"\n");
          }

         public void println(char []c) throws IOException {
            writer.write(c+"\n");
         }

         public  void close() throws IOException {
            writer.close();
         }

    }
    public static long gcd(long a,long b){
        return(a==0?b:gcd(b%a,a));
    }
    public static long lcm(long a,long b){
        //return (a*b)/gcd(a,b);
        //this is modified to avoid integer overflow by multiplying a*b
        return((a/gcd(a,b))*b);
    }
    public static void initialize_io_redirection()throws IOException{
        try{
            boolean MP = System.getProperty("MY_PC")!=null;
            if(MP){
                fs = new FastReader("input.txt");
                op = new OutputWriter("output.txt");
                System.setOut(new PrintStream(new File("output.txt")));
            }
            else{
                fs = new FastReader();
                op = new OutputWriter(System.out);
            }
       }
       catch(Exception e){
            fs = new FastReader();
            op = new OutputWriter(System.out);
       }
    }
   static FastReader fs;
   static OutputWriter op;
    public static void main(String[] args)throws IOException{
        initialize_io_redirection();
        int t = fs.nextInt();
        while(t-- > 0)
            solve();
        op.close();
    }

    public static void solve()throws IOException{
    	int n=fs.nextInt();
    	String str = fs.nextLine();
        char []arr = str.toCharArray();
        Arrays.sort(arr);
        int c=0;
        for(int i=0;i<n;i++){
        	char ch=str.charAt(i);
        	if(arr[i]!=ch)
        		c++;
        }
        System.out.println(c);
    }
}

