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
       String numbers = "0123456789";
    String lower_case = "abcdefghijklmnopqrstuvwxyz";
    String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    String special_characters = "!@#$%^&*()-+";
        //if(n < 6)
          //  return (6 - n);
        int no, lc, uc, sc;
        no = lc = uc = sc =0;
        int c = 0;
        for(int x = 0; x < numbers.length(); x++)  //Numbers
            {
                if(password.contains(numbers.charAt(x) + ""))
                    no++;
            }
        for(int x = 0; x < lower_case.length(); x++)  //Numbers
            {
                if(password.contains(lower_case.charAt(x) + ""))
                    lc++;
            }
        for(int x = 0; x < upper_case.length(); x++)  //Numbers
            {
                if(password.contains(upper_case.charAt(x) + ""))
                    uc++;
            }
        for(int x = 0; x < special_characters.length(); x++)  //Numbers
            {
                if(password.contains(special_characters.charAt(x) + ""))
                    sc++;
            }
        if(no == 0)
            c++;
        if(uc == 0)
            c++;
        if(lc == 0)
            c++;
        if(sc == 0)
            c++;   
        if(n < 6  && c + n < 6)
            return 6 - n;
        else
            return c;
    }

    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();
    }
}