N,S,K=map(int,input().split())
A=[int(input()) for i in range(N)]

MIN=1<<60

for a in A:
    MIN=min(MIN,abs(a-S))

if MIN>K:
    print("Unlucky!")
else:
    for i in range(N):
        if MIN==abs(A[i]-S):
            print(i+1)
            break