import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    switch (S) {
      case "AAA":
      case "BBB":
        System.out.println("No");
        break;
      case "AAB":
      case "ABA":
      case "BAA":  
      case "BBA":
      case "BAB":
      case "ABB":
        System.out.println("Yes");
        break;
    }
  }
}
/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