import java.util.*;

public class Main{
    public static void main(String[]args){
        Scanner sc = new Scanner(System.in);
        String str = sc.next();
        String[]array=str.split("");
        if(array[0].equals(array[2]) && array[1].equals(array[2]))
        System.out.println("No");
        else
        System.out.println("Yes");
     }
}
/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