import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class CountChar {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		String input = scanner.nextLine();
		scanner.close();
		System.out.print(count(input));
	}

	private static int count(String input) {
		int n = 0;
		Set<Character> set = new HashSet<>();
		for (int i = 0; i < input.length(); i++) {
			if (input.charAt(i) >= 0 && input.charAt(i) <= 127)
				set.add(input.charAt(i));
		}
		n = set.size();
		return n;
	}
}