import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class MaginSquare {

    /**
     * @param args the command line arguments
     */
    
    static int minimumNumber(int n, String s) {
        // Return the minimum number of characters to make the password strong
        String num = "0123456789" ;
        String low = "abcdefghijklmnopqrstuvwxyz" ; 
        String up = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" ;
        String spec = "!@#$%^&*()-+";
        
        int check = 0;
        for(int i=0;i<s.length();i++)
        {
            if(num.contains(s.charAt(i)+"")) check |= 1;
            if(low.contains(s.charAt(i)+"")) check |= 2;
            if(up.contains(s.charAt(i)+"")) check |= 4;
            if(spec.contains(s.charAt(i)+"")) check |= 8;
        }
        
        int count =0;
        for(int i=0;i<=3;i++){
            if((check>>i)%2==0) count ++ ;
        }
        //System.out.println(count);
        if(count+s.length()<6) count += 6 - count - s.length() ; 
        return count ;
    }

    public static void main(String[] args) {
        //System.out.println("abc".contains('a'+""));
        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();
    }
    
}