import java.util.*;
class Main{
	public static void main(String[]args){
      Scanner in = new Scanner(System.in);
      String n = in.nextLine();
      int c =0, d=0;
      for(int i = 0 ; i < n.length() ; i++){
      	if(n.charAt(i)=='A')
          c++;
        else if(n.charAt(i)=='B')
          d++;
      }
      if(c==2)
        System.out.println("Yes");
      else if(d==2)
         System.out.println("Yes");
      else
         System.out.println("No");
    }
}
/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