# -*- coding: utf-8 -*-
"""
No.571 3人兄弟（その２）
https://yukicoder.me/problems/no/571

"""
import sys
from sys import stdin
input = stdin.readline


def main(args):
    brothers = []

    H, W = map(int, input().split())
    brothers.append([-H, W, "A"])
    H, W = map(int, input().split())
    brothers.append([-H, W, "B"])
    H, W = map(int, input().split())
    brothers.append([-H, W, "C"])

    brothers.sort()
    for _, _, name in brothers:
        print(name)


if __name__ == '__main__':
    main(sys.argv[1:])