def main():
    shops, favorite, diff_upper = map(int, input().split())
    ramens_diff = []
    for idx in range(1, shops+1):
        ramens_diff.append((idx, int(input())-favorite))

    ramens_liked = list(filter(
        lambda ramen: abs(ramen[1]) <= diff_upper,
        ramens_diff
    ))

    if ramens_liked:
        print(min(ramens_liked, key=lambda ramen: abs(ramen[1]))[0])
    else:
        print("Unlucky!")


if __name__ == "__main__":
    main()