import java.util.Scanner;

public class Solution {

	static int minimumNumber(int n, String password) {
		int chNeeded = (password.length() < 6) ? 6 - password.length() : 0;
		int isDigit = 0;
		int isLower = 0;
		int isUpper = 0;
		int isSpecial = 0;
		for (int i = 0; i < password.length(); i++) {
			if (Character.isDigit(password.charAt(i))) {
				isDigit = 1;
			} else if (Character.isLowerCase(password.charAt(i))) {
				isLower = 1;
			} else if (Character.isUpperCase(password.charAt(i))) {
				isUpper = 1;
			} else if (isSpecial(password.charAt(i))) {
				isSpecial = 1;
			}
		}
		int total = isDigit + isLower + isUpper + isSpecial;
		return (chNeeded > 4 - total ? chNeeded : 4 - total);

	}

	static boolean isSpecial(char ch) {
		if (ch == '!' || ch == '@' || ch == '#' || ch == '$' || ch == '%'
				|| ch == '%' || ch == '^' || ch == '&' || ch == '*'
				|| ch == '(' || ch == ')' || ch == '-' || ch == '+') {
			return true;
		}
		return false;
	}

	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();
	}
}