n, s, k = map(int, input().split())
ans = -1
min_s = k + 1
for i in range(n):
    a = int(input())
    if abs(a - s) < min_s:
        min_s = abs(a - s)
        ans = i + 1
if ans == -1:
    print("Unlucky!")
else:
    print(ans)