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 = "!@#$%^&*()-+";
        
        boolean b1=false,b2=false,b3=false,b4=false;
        
        for(char c : password.toCharArray()){
            if(numbers.indexOf(c) != -1)
                b1=true;
            if(lower_case.indexOf(c) != -1)
                b2=true;
            if(upper_case.indexOf(c) != -1)
                b3=true;
            if(special_characters.indexOf(c) != -1)
                b4=true;            
        }
        
        int changes = 0;
        if(!b1)
            ++changes;
        if(!b2)
            ++changes;
        if(!b3)
            ++changes;
        if(!b4)
            ++changes;        
        
        changes = Math.max(changes,6-password.length());
        return changes;
        

        
    }

    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();
    }
}