import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		String S = sc.next();
		String isDiff = "No";

		char station = S.charAt(0);
		for (int i = 1; i < 3; i++) {
			char temp = S.charAt(i);
			if (station != temp) {
				isDiff = "Yes";
			}
		}

		System.out.println(isDiff);

		sc.close();
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz