import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		Map<Integer,String> map = new HashMap<>();
		map.put(sc.nextInt(),"A");
		map.put(sc.nextInt(),"B");
		map.put(sc.nextInt(),"C");
		Object[] mapkey = map.keySet().toArray();
		Arrays.sort(mapkey);
		
		for (int i=2; i>=0; i--) {
			System.out.println(map.get(mapkey[i]));
		}
	}
}