import java.util.*;
public class Main {
    public static void main(String args[]) {
        Scanner scan=new Scanner(System.in);
        String s= scan.nextLine();
        String ans=new String();
        if(s.equals("ABC"))
        {
            ans="ARC";
        }
        else
        ans="ABC";
        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