N,S,K = map(int,input().split())
delta = 100
ans = -1
for _ in range(N):
    A = int(input())
    if abs(A - S) <= K:
        if abs(A - S) < delta:
            delta = abs(A - S)
            ans = _ + 1
if ans == -1:
    print("Unlucky!")
else:
    print(ans)