import java.util.Scanner;

public class Main{
	public static void main(String[]org){
    	
      Scanner scan = new Scanner(System.in);
      String s = scan.nextLine();
      String result = "";
      if(s.charAt(1)=='B'){
		result = "ARC";
      }
      else{
        result ="ABC";
      }
     System.out.println(result);
	}
}

/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