import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String str = scan.nextLine();
 
        checker(str);
        scan.close();
    }
  
public static void checker(String title){
  if(title.equals("ARC")){
      System.out.println("ABC");
   // return;
  }else if(title.equals("ABC")){
      System.out.println("ARC");
   // return;
  } else{
    System.err.println("コンテスト名が正しくありません。");
   // return;
  }
}
}
/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