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

public class Solution {
    static boolean is(char a)
    {
        String s="!@#$%^&*()-+";
        for(int i=0;i<12;i++)
            if(a==s.charAt(i))
                return true;
        return false;
        
    }
    static int minimumNumber(int n, String s) {
       boolean isDigit=false,isLower=false,isUpper=false,isSpecial=false;
        int count=4;
        int sum=0;
       for(int i=0;i<n&&count>0;i++)
       {    char a=s.charAt(i);
           if(!isDigit&&a>='0'&&a<='9')
           {
               isDigit=true;
               count--;
           }
           else  if(!isLower&&a>='a'&&a<='z')
           {
               isLower=true;
               count--;
           }
            
           else  if(!isUpper&&a>='A'&&a<='Z')
           {
               isUpper=true;
               count--;
           }
            else if(!isSpecial&&is(a))
            {
                isSpecial=true;
                count--;
            }
       }
        sum=6-n>=count?6-n:count;
        return sum;
    }

    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();
    }
}