N, S, K = map(int, input().split())

res = -100  # -INF
res_idx = 0
for i in range(1, N + 1):
    A = int(input())
    if abs(A - S) < abs(res - S):
        res = A
        res_idx = i
if abs(res - S) <= K:
    print(res_idx)
else:
    print("Unlucky!")