import java.util.Scanner;
class Main {
	public static void main(String[] args){
    	Scanner stdIn = new Scanner(System.in);
    	
        String a = stdIn.next();
      	if(a.equals("ABC"))
      		System.out.println("ARC");
      	if(a.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