I took a long while to hack at this problem and then I decided to be cheeky and post it to my door at work. If you know the answer, please keep it to yourself. If you don’t know the answer, don’t feel really bad that you can’t figure it out – it took smarter people than I a long time to get the answer. If you want to know if you are right, feel free to email me or iMessage me with your answer and I’ll let you know if you are right or not.