import java.util.*;
 
class Main {
 
    public static void main (String args[])
    {
        Scanner in = new Scanner(System.in);
       

        String compet = in.nextLine();

        if(compet.equals("ABC"))
        System.out.println("ARC");
       else if(compet.equals("ARC"))
        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