import sys
readline = sys.stdin.readline

N,S,K = map(int,readline().split())
ans = -1
best_diff = 1 << 60
for i in range(N):
    A = int(readline())
    diff = abs(A - S)
    if diff > K:
        continue
    if diff < best_diff:
        best_diff = diff
        ans = i + 1

if ans == -1:
    print("Unlucky!")
else:
    print(ans)