n, s, k = map(int, input().split())
a = [int(input()) for _ in range(n)]

best_diff = float('inf')
best_idx = -1

for i in range(1, n + 1):
    current = a[i - 1]
    diff = abs(current - s)
    if diff <= k:
        if diff < best_diff:
            best_diff = diff
            best_idx = i

print(best_idx if best_idx != -1 else "Unlucky!")