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

public class Solution {

	public static void main(String args[]) throws IOException {
		/* Enter your code here. Read input from STDIN. Print output to STDOUT */
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String special_characters = "!@#$%^&*()-+";
		int n = Integer.parseInt(in.readLine());
		String s = in.readLine();
		int index1 = -1;
		int index2 = -1;
		int index3 = -1;
		int index4 = -1;
		for (int i = 0; i < s.length(); i++) {
			char c = s.charAt(i);
			if (Character.isAlphabetic(c) && Character.isLowerCase(c)) {
				index1 = i;
			}
			if (Character.isAlphabetic(c) && Character.isUpperCase(c)) {
				index2 = i;
			}
			for (int j = 0; j < special_characters.length(); j++) {
				if (special_characters.charAt(j) == c) {
					index3 = i;
					break;
				}
			}
			if (Character.isDigit(c)) {
				index4 = i;
			}
		}
		int res = 0;
		if (index1 < 0) {
			res++;
		}
		if (index2 < 0) {
			res++;
		}
		if (index3 < 0) {
			res++;
		}
		if (index4 < 0) {
			res++;
		}
		System.out.println(Math.max(res, 6 - s.length()));

	}
}