def main():
    n, s, k = map(int, input().split())

    mi = 100
    ans = -1
    for i in range(1, n + 1):
        a = int(input())
        diff = abs(s - a)
        if diff <= k and diff < mi:
            mi = diff
            ans = i

    if ans == -1:
        print("Unlucky!")
    else:
        print(ans)


if __name__ == "__main__":
    main()