import java.util.Scanner;

public class Main{ 
	public static void main(String args[]){
    	String x = new String("ABC");
      	String y = new String("ARC");
      	Scanner scan = new Scanner(System.in);
      	String s = scan.next();
      	// System.out.println(s);
      	// System.out.println(x);
      	// System.out.println(y);
      	if(s.equals(x)) System.out.println(y);
      	else System.out.println(x);
      	scan.close();
    }
}
/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