using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static int minimumNumber(int n, string password) {
        // Return the minimum number of characters to make the password strong
        string numbers = "0123456789";
        string lower_case = "abcdefghijklmnopqrstuvwxyz";
        string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        string special_characters = "!@#$%^&*()-+";
        int length=6;
        bool cn=false;
        bool cl=false;
        bool cu=false;
        bool cs=false;
        if(n<=3)
            return length-n;
        for(int i=0;i<n;i++)
        {
            if(!cn)
            if(numbers.Contains(password[i]))
                cn=true;
            if(!cl)
                if(lower_case.Contains(password[i]))
                    cl=true;
            if(!cu)
                if(upper_case.Contains(password[i]))
                    cu=true;
            if(!cs)
                if(special_characters.Contains(password[i]))
                    cs=true;
            if(cn && cl && cu && cs)
                break;               
        }
        int count=0;
        int len=0;
        if(cn)
            count++;
        if(cl)
            count++;
        if(cu)
            count++;
        if(cs)
            count++;
        if(n<6)
            len=6-n;
        if(4-count>len)
            return 4-count;
        else
            return len;
        
    }

    static void Main(String[] args) {
        int n = Convert.ToInt32(Console.ReadLine());
        string password = Console.ReadLine();
        int answer = minimumNumber(n, password);
        Console.WriteLine(answer);
    }
}