n, s, k = map(int, input().split())
u = s + k
l = s - k


ans = []
tmp = 200
for i in range(n):
    a = int(input())
    b = abs(s - a)
    if b <= k:
        if b < tmp:
            tmp = b
            number = i + 1
            ans.append([number, tmp])

if len(ans) == 0:
    print("Unlucky!")
else:
    for num, val in sorted(ans, key=lambda x : [x[1], x[0]]):
        print(num)
        break