import java.util.*;

public class Main {

  static Scanner scan = new Scanner(System.in);

  public static void main(String[] args) {
    String t = scan.next();

    System.out.print(t.equals("ARC") ? "ABC" : "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