N, S, K = map(int, input().split())
A = [int(input()) for _ in range(N)]

shop = -1
diff_min = 1 << 60

for i in range(N):
    t = abs(A[i]-S)
    if t < diff_min:
        diff_min = t
        shop = i + 1

if diff_min > K:
    print("Unlucky!")
else:
    print(shop)