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) {
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        // Return the minimum number of characters to make the password strong
        int u=0,l=0,s=0,d=0;
        int fu=0,fl=0,fs=0,fd=0;
        for(int x=0;x<n;x++)
        {
            char ch=password.charAt(x);
            if(Character.isDigit(ch) && fd==0)
            {
                d=1;
                fd=1;
            }
            else if(Character.isLowerCase(ch) && fl==0)
            {
                l=1;
                fl=1;
            }
            else if(Character.isUpperCase(ch) && fu==0)
            {
                u=1;
                fu=1;
            }
            else if(special_characters.indexOf(ch)>-1 && fs==0)
            {
                s=1;
                fs=1;
            }
        }
        if(password.length()<6)
        {
            return ((1-u+1-l+1-d+1-s)<6-n?6-n:1-u+1-l+1-d+1-s);
        }
        else 
            return 1-u+1-l+1-d+1-s;
    }

    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();
    }
}