def Main():
    
    n,s,k=map(int,input().split())
    now=10**13
    ans=-1
    for i in range(n):
        a=int(input())
        g=abs(a-s)
        if g<now and g<=k:
            now=g
            ans=i+1
    if ans==-1:
        print("Unlucky!")
    else:
        print(ans)
    




    
Main()