import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution 
{
    public static void main(String[] args) 
    {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String pass = in.next();
        int count=0;
        int len = pass.length();
        
        int flaga=0;
        int flagb=0;
        int flagc=0;
        int flagd=0;
        int flage=0;
        
        if(len < 6)
        {
            count = 6-len;
            int check=0;
            
            for(int i=0 ; i<len ; i++)
            {
                if( pass.charAt(i)>='0' && pass.charAt(i)<='9')
                    flaga=1;
                else if(pass.charAt(i)>='A' && pass.charAt(i)<='Z' )
                    flagb=1;
                else if(pass.charAt(i)>='a' && pass.charAt(i)<='z')
                    flagc=1;
                else if(pass.charAt(i)>='!' && pass.charAt(i)<='@')
                    flagd=1;
            }    
            if(flaga==0)
                check++;
            if(flagb==0)
                check++;
            if(flagc==0)
                check++;
            if(flagd==0)
                check++;
            
            if(count < check)
                count=check;
            
        }
        else
        {
            for(int i=0 ; i<len ; i++)
            {
                if( pass.charAt(i)>='0' && pass.charAt(i)<='9')
                    flaga=1;
                else if(pass.charAt(i)>='A' && pass.charAt(i)<='Z' )
                    flagb=1;
                else if(pass.charAt(i)>='a' && pass.charAt(i)<='z')
                    flagc=1;
                else if(pass.charAt(i)>='!' && pass.charAt(i)<='@')
                    flagd=1;
            }    
            if(flaga==0)
                count++;
            if(flagb==0)
                count++;
            if(flagc==0)
                count++;
            if(flagd==0)
                count++;
        }
       
        
        System.out.println(count);
        in.close();
    }
}