Feel around the marbles. All the marbles feel exactly the same. And if you're able to pick two green marbles, if you're able to take one marble out of the bag, it's green, you put it down on the table, then put your hand back in the bag and take another marble. And if that one is also green, then you're going to win the prize. You're going to win the prize of $1 if you get two greens. We say, well, this sounds like an interesting game. How much does it cost to play?