n,s,k=map(int,input().split())

S = []
for i in range(n):
    a = int(input())
    for k in range(k+1):
        if abs (a - s) <= k:
            S.append([i,abs(a-s)])
            break

dp = 10**7
ans = 0
if S != []:
    for i, val in S:
        if dp - val > 0 :
            dp = val
            ans = i+1
    print(ans)
else:
    print('Unlucky!')