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
        boolean digit = false;
        boolean lowercase = false;
        boolean uppercase = false;
        boolean special = false;
        for(int i = 0; i<n; i++){
            char c = password.charAt(i);
            if(Character.isDigit(c))
                digit = true;
            else if(Character.isUpperCase(c))
                uppercase = true;
            else if(Character.isLowerCase(c))
                lowercase = true;
            else
                special = true;
        }
        int e = 0;
        if(!digit)e++;
        if(!lowercase)e++;
        if(!uppercase)e++;
        if(!special)e++;
        if(e+n < 6)e = 6-n;
        return e;
    }

    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();
    }
}