import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        String[] lines = getStdin();
        String str = lines[0];
        
        String a = "ABC";
        String b = "ARC";
        
        if (str.equals(a)){
            System.out.println(b);
        } else {
            System.out.println(a);
        }

   }
  
  private static String[] getStdin() {
    Scanner scanner = new Scanner(System.in);
    ArrayList<String> lines = new ArrayList<>();
    while (scanner.hasNext()) {
      lines.add(scanner.nextLine());
    }
    return lines.toArray(new String[lines.size()]);
  }
  
}

/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