=>[color:"#3A495A"]Still asuming the 2 monks: He can only know it if the other monk doesn't jump on the 1st day either (then the both monks have a dot, and they would jump on the 2nd day). If one of both monks jump on the first day, then the one that jumped only has a dot on his head.
Now back to the normal story, there they jump on the third day,so meaning that there are 3 monks having dots on their heads. So they jump when the number of dots that they see, overrides it with one.[/color]
