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;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.util.*;
import static java.lang.Math.pow;
import static java.lang.Math.log;
import static java.lang.Math.ceil;
import static java.lang.Math.sqrt;
import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.lang.Math.abs;
import static java.lang.System.out;
import java.math.BigInteger;
import java.util.stream.Collectors;


public class Main {

	static FastReader sc;
    static PrintWriter out;
    
	
	 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()); 
	        } 
	  
	        String nextLine() 
	        { 
	            String str = ""; 
	            try
	            { 
	                str = br.readLine(); 
	            } 
	            catch (IOException e) 
	            { 
	                e.printStackTrace(); 
	            } 
	            return str; 
	        } 
	    }
	 
	 
	 static void ruffleSort(long[] a) {
			int n=a.length;
			Random r=new Random();
			for (int i=0; i<a.length; i++) {
				long oi=r.nextInt(n), temp=a[i];
				a[i]=a[(int)oi];
				a[(int)oi]=temp;
			}
			Arrays.sort(a);
		}
	static void ruffleSort(int[] a) {
			int n=a.length;
			Random r=new Random();
			for (int i=0; i<a.length; i++) {
				int oi=r.nextInt(n), temp=a[i];
				a[i]=a[oi];
				a[oi]=temp;
			}
			Arrays.sort(a);
		}
	 
	 
	 static int gcd(int a, int b)
	    {
	      if (b == 0)
	        return a;
	      return gcd(b, a % b);
	    }
	 
	 static int lowerBound(int[] a, int low, int high, int element) {
		    while (low < high) {
		        int middle = low + (high - low) / 2;
		        if (element > a[middle]) {
		            low = middle + 1;
		        } else {
		            high = middle;
		        }
		    }
		    return low;
		}

		static int upperBound(int[] a, int low, int high, int element) {
		    while (low < high) {
		        int middle = low + (high - low) / 2;
		        if (a[middle] > element) {
		            high = middle;
		        } else {
		            low = middle + 1;
		        }
		    }
		    return low;
		}
	 
	 static class Pair {
		    long x;
		    long y;
		  
		   
		public Pair(long x, long y)
		    {
		        this.x = x;
		        this.y = y;
		    }
		}
	 public void solve() {
			int t=sc.nextInt();
			while(t-->0) {
				cal();
		    }
		 }
	 
	 public static String sortString(String inputString)
	    {
	        
	        char tempArray[] = inputString.toCharArray();
	          
	        
	        Arrays.sort(tempArray);
	          
	       
	        return new String(tempArray);
	    }
	 
	 static void cal() {
		  int n=sc.nextInt();
		  String s=sc.nextLine();
		  String t=s;
		  
		  String sorted= sortString(t);
		  
		  int c=0;
		  
	//	  System.out.println(s+" "+sorted);
		  
		  for(int i=0;i<s.length();i++) {
			  if(s.charAt(i)!=sorted.charAt(i)) {
				  c++;
			  }
		  }
		  
		  System.out.println(c);
	 }
	 
	
	
	public static void main(String[] args) throws IOException {
		sc = new FastReader();
	    out = new PrintWriter(System.out);
	    new Main().solve();
	    out.flush();
	}

}
