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 count=0,no=0,lo=0,up=0,sp=0;
        char ch;
        String str;
        String numbers = "0123456789";
String lower_case = "abcdefghijklmnopqrstuvwxyz";
String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
String special_characters = "!@#$%^&*()-+";
        
        for(int i=0;i<n;i++)
        {
            //ch=password.charAt(i);
            str=password.substring(i,i+1);
            if(numbers.indexOf(str)>=0)
            {//System.out.println("n");
                no++;
            }
            else if(lower_case.indexOf(str)>=0)
            {  lo++;
          //  System.out.println("l");
            
            }
           else if(upper_case.indexOf(str)>=0)
           {up++;
          // System.out.println("u");
           }
            else if(special_characters.indexOf(str)>=0)
            {sp++;
            //System.out.println("s");
            }
        }
        if(no==0)
            count++;
        if(lo==0)
            count++;
        if(up==0)
            count++;
        if(sp==0)
            count++;
        if(n+count<6)
        {
           // System.out.println(count);
            count+=(6-(n+count));}
        if(no>0&&lo>0&&up>0&&sp>0&&n>=6)
            return 0;
        
       return count;     
        
    }

    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();
    }
}