def main():
    members = {}
    for _ in range(int(input())):
        A, B = input().split()

        members[A] = "cheater"
        if B not in members:
            members[B] = "clever"

    for clever_member in filter(lambda name: members[name] == "clever", members):
        print(clever_member)


if __name__ == "__main__":
    main()