import java.util.*;

public class Main {

    static int gcd (int a, int b) {return b>0?gcd(b,a%b):a;}
    static int mod = 1000000007;

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