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 lowerCase = "abcdefghijklmnopqrstuvwxyz";
        String upperCase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String specialCharacters = "!@#$%^&*()-+";
        int minLength = 6;
        int lengthLeft = 6 - n;
        boolean numberBln = false;
        boolean lowerCaseBln = false;
        boolean upperCaseBln = false;
        boolean specialCharactersBln = false;
        int counter = 0;
        
        for(int i = 0; i < password.length(); i++){
            if(numbers.indexOf(password.charAt(i)) != -1){
                numberBln = true;
            }
            else if(lowerCase.indexOf(password.charAt(i)) != -1){
                lowerCaseBln = true;
            }
            else if(upperCase.indexOf(password.charAt(i)) != -1){
                upperCaseBln = true;
            }
            else if(specialCharacters.indexOf(password.charAt(i)) != -1){
                specialCharactersBln = true;
            }
            if(numberBln && lowerCaseBln && upperCaseBln && specialCharactersBln) break;
        }
        
        if(!numberBln)counter++;
        if(!lowerCaseBln)counter++;
        if(!upperCaseBln)counter++;
        if(!specialCharactersBln)counter++;
        
        return Math.max(lengthLeft, counter);
    }

    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();
    }
}