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

public class Solution {
    

    static int minimumNumber(int n, String password) {
        // Return the minimum number of characters to make the password strong
        int len=n;
        
        boolean isnum=false, islower=false, isupper=false, ischar=false;
        for(int i=0;i<len;i++){
            if(password.charAt(i)>='0'&& password.charAt(i)<='9')
                isnum=true;
            else if(password.charAt(i)>='a'&& password.charAt(i)<='z')
                islower=true;
            else if(password.charAt(i)>='A'&& password.charAt(i)<='Z')
                isupper=true;
            //else if(password.charAt(i)=='!'| password.charAt(i)=='@'| password.charAt(i)=='#'| password.charAt(i)=='$' | password.charAt(i)=='%' password.charAt(i)=='^' |password.charAt(i)=='*' |password.charAt(i)=='&'|password.charAt(i)=='('|password.charAt(i)==')'|password.charAt(i)=='+'|password.charAt(i)=='-')//
            else
                ischar=true;
        }
        
        if(!isnum) len++;
         if(!islower) len++;
         if(!isupper) len++;
         if(!ischar) len++;
        
        if(len<=6)
            len=6;
        
        return len-n;
        

   
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String password = in.next();
        int answer = minimumNumber(n, password);
        System.out.println(answer);
        in.close();
    }
}