import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
      String s1 = "ABC";
      String s2 = "ARC";
      boolean t1 = true;
      boolean t2 = true;
		for(int i = 0;i<s.length();i++){
         if(s.charAt(i)!=s1.charAt(i)){
            t1 = false;
            break;
         }
      }
      	for(int i = 0;i<s.length();i++){
         if(s.charAt(i)!=s2.charAt(i)){
            t2 = false;
            break;
         }
      }
       if(t1==true){
          System.out.println(s2);
           }
       if(t2==true){
          System.out.println(s1); 
          }
	}
}

/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