import java.util.Arrays;
import java.util.Scanner;

public class Solution {
    private static final char[] special = "!@#$%^&*()-+".toCharArray();

    static int minimumNumber(int n, String password) {
        boolean hasUpper, hasLower, hasDigit, hasSpecial = hasDigit = hasLower = hasUpper = false;
        int count = 4;
        for (int i = 0; i < n; i++) {
            char c = password.charAt(i);
            if (!hasSpecial && Arrays.binarySearch(special, c) >= 0) {
                hasSpecial = true;
                count--;
            }
            if (!hasLower && Character.isLowerCase(c)) {
                hasLower = true;
                count--;
            }
            if (!hasUpper && Character.isUpperCase(c)) {
                hasUpper = true;
                count--;
            }
            if (!hasDigit && Character.isDigit(c)) {
                count--;
                hasDigit = true;
            }
        }
        return n < 6 ? (Math.max(6 - n, count)) : count;
        // Return the minimum number of characters to make the password strong
    }

    public static void main(String[] args) {
        Arrays.sort(special);
        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();
    }
}