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.*;
import java.lang.*;
import java.io.*;

public class Main
{
    static long mod = (int)1e9+7;
    public static void main (String[] args) throws java.lang.Exception
    {
        FastReader sc =new FastReader();

        int t=sc.nextInt();
   
     // int t=1;
   
        while(t-->0)
        {
            int n=sc.nextInt();
            String s=sc.next();
            char a[]=s.toCharArray();
            for(int i=0;i<n;i++)
            {
                for(int j=0;j<n;j++)
                {
                    if(a[i]<a[j])
                    {
                        char temp=a[i];
                        a[i]=a[j];
                        a[j]=temp;
                    }
                }
            }
            int count=0;
            for(int i=0;i<n;i++)
            {
                char ch=s.charAt(i);
                if(a[i]!=ch)
                    count++;
            }
            System.out.println(count);
        }
    }



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());
        }
       
        float nextFloat()
        {
            return Float.parseFloat(next());
        }
 
        String nextLine()
        {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
       
        int[] readArray(int n) {
int[] a=new int[n];
for (int i=0; i<n; i++) a[i]=nextInt();
return a;
}

long[] readArrayLong(int n) {
long[] a=new long[n];
for (int i=0; i<n; i++) a[i]=nextLong();
return a;
}

    }
   
    public static int[] radixSort2(int[] a)
{
int n = a.length;
int[] c0 = new int[0x101];
int[] c1 = new int[0x101];
int[] c2 = new int[0x101];
int[] c3 = new int[0x101];
for(int v : a) {
c0[(v&0xff)+1]++;
c1[(v>>>8&0xff)+1]++;
c2[(v>>>16&0xff)+1]++;
c3[(v>>>24^0x80)+1]++;
}
for(int i = 0;i < 0xff;i++) {
c0[i+1] += c0[i];
c1[i+1] += c1[i];
c2[i+1] += c2[i];
c3[i+1] += c3[i];
}
int[] t = new int[n];
for(int v : a)t[c0[v&0xff]++] = v;
for(int v : t)a[c1[v>>>8&0xff]++] = v;
for(int v : a)t[c2[v>>>16&0xff]++] = v;
for(int v : t)a[c3[v>>>24^0x80]++] = v;
return a;
}


   
    public static HashMap<Integer, Integer> sortByValue(HashMap<Integer, Integer> hm)
    {
        // Create a list from elements of HashMap
        List<Map.Entry<Integer, Integer> > list =
               new LinkedList<Map.Entry<Integer, Integer> >(hm.entrySet());
 
        // Sort the list
        Collections.sort(list, new Comparator<Map.Entry<Integer, Integer> >() {
            public int compare(Map.Entry<Integer, Integer> o1,
                               Map.Entry<Integer, Integer> o2)
            {
                return (o1.getValue()).compareTo(o2.getValue());
            }
        });
         
        // put data from sorted list to hashmap
        HashMap<Integer, Integer> temp = new LinkedHashMap<Integer, Integer>();
        for (Map.Entry<Integer, Integer> aa : list) {
            temp.put(aa.getKey(), aa.getValue());
        }
        return temp;
    }
    static int DigitSum(int n)
    {
        int r=0,sum=0;
        while(n>=0)
        {
            r=n%10;
            sum=sum+r;
            n=n/10;
        }
        return sum;
    }
}