import java.util.*;

public class Main{
	public static void main(String arga[]){
		
		Scanner sc = new Scanner(System.in);
		String a = sc.next(); 
		String b = "ABC";
		String c = "ARC";
		
		if(a.equals(b)){
			System.out.println("ARC");
		}
		else if(a.equals(c)){
			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