def main():
    A = tuple(map(int, input().split()))
    B = tuple(map(int, input().split()))
    C = tuple(map(int, input().split()))

    l = [("A", A),
         ("B", B),
         ("C", C)]
    for name, _ in sorted(l,
                          key=lambda x: x[1],
                          reverse=True):
        print(name)

if __name__ == '__main__':
    main()