Comment in source:
"This one is courtesy of Jimmy Cha, who showed it to me at the Fujitsu in SF recently. He used it for betting, as follows: you get to look at the problem for as long as you want, then when you think you have the answer, you bet Jimmy $1. If you make a single mistake he keeps the $1, or if (ha-ha) you happen to have solved it correctly, he pays you $5. Last time I checked he was $14 ahead. Note that this means there must be a simple (but wrong) line of play which appears to succeed (but fails in a subtle way). Anyway, I promise you LOTS of surprises in working this one out.