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
        int digit=0,lower=0,upper=0,special=0,count=0,need=0,x;
        String s="!@#$%^&*()-+";
        for(int i=0;i<n;i++)
        {
            if(Character.isDigit(password.charAt(i)))
                digit=1;
            else if(Character.isUpperCase(password.charAt(i)))
                upper=1;
            else if(Character.isLowerCase(password.charAt(i)))
                lower=1;
            else
                special=1;
        }
        count=digit+lower+upper+special;
        need=4-count;
        if(n>6)
            return need;
        else
        {
            x=n+need;
            if(x<6)
                need=need+(6-x);
            return need;
        }
    }

    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();
    }
}