import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		 String result = new Scanner(System.in).next();
		 if(result.equals("ARC")) {
			 result = "ABC";
		 }
		 else {
			 result = "ARC";
		 }
		 System.out.println(result);
		 
	}

}

/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