import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String S=sc.nextLine();
    String str1="ABC";
    String str2="ARC";
    if(S.equals(str1)){
      System.out.println("ARC");
    }else if(S.equals(str2)){
      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