import java.util.Scanner;

/**
 *
 * https://atcoder.jp/contests/abc158/tasks/abc158_a
 *
 * @author shouma
 *
 */

public class Main {
	public static void main(String args[]) {
		//strにはAかBの文字列が入る。(３文字)
		Scanner scan = new Scanner(System.in);
		String str = scan.nextLine();
		//AAAのみやBBBのみだと、バスは運行しない→Noを出力
			if(str.contains("AAA") || str.contains("BBB")){
				System.out.println("No");
			}else {
				System.out.println("Yes");
			}
        scan.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