import java.util.*;
import java.lang.*;
public class Main
{
    public static void main (String[] args)
    {
        Scanner sc = new Scanner(System.in);
        String s=sc.nextLine();
        if(s.charAt(1)=='R')
            System.out.println("ABC");
        else
            System.out.println("ARC");
    }
}
/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