import java.util.*;
 
public class Main{
  
 public static void main(String arg[])
 {
  Scanner sc=new Scanner(System.in);
   String s=sc.next();
   if(s.charAt(s.length()-2)=='B')System.out.println("ARC");
   else System.out.println("ABC");
 }
}

/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