There are four guys standing in a line. They need to find out which color their hats are. They can't see their own hat color and only can see to the right. They can't see the person behind the seperation wall. If they know their hat color they can shout it and will win a million dollars. If they're wrong they die.
Who shouts and therefore wins the million dollars?
[ I found this puzzle on another site and thought it was worth sharing, not sure if it's allowed ]