import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        StringBuilder sb = new StringBuilder();
        List<String> list = new ArrayList<>();
        int num = 3;
        for(int i = 0; i < num; i++) {
            char c = (char)('A' + i);
            String s = sc.next() + c;
            list.add(s);
        }
        Collections.sort(list);
        Collections.reverse(list);
        for(String tmp: list) {
            System.out.println(tmp.charAt(tmp.length()-1));
        }
    }
}