import java.util.Scanner;


public class Main {

	public static void main(String[] args)  {

		Scanner sc = new Scanner(System.in);
		String A =  sc.next();
		String ans = "ABC";
		
		if(A.equals(ans)) {
			ans = "ARC";
		}
		
		System.out.println(ans);
	}



}


/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