import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Scanner;

public class No571 {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        LinkedHashMap<String, Integer[]> map = new LinkedHashMap<>();
        map.put("A", new Integer[]{s.nextInt(), s.nextInt()});
        map.put("B", new Integer[]{s.nextInt(), s.nextInt()});
        map.put("C", new Integer[]{s.nextInt(), s.nextInt()});
        map.entrySet().stream()
            .sorted(Map.Entry.comparingByValue((o1, o2) -> {
                if (o1[0] < o2[0] || o1[0] == o2[0] && o1[1] < o2[1]) {
                    return 1;
                }
                return -1;
            }))
            .forEach(e -> System.out.println(e.getKey()));
    }
}