Consider a generalized second price (GSP) auction used by a search engine for allocating search ads. There are in total 2 slots to be sold. The top slot will receive 500 clicks while the second slot will receive 200 clicks. Suppose the auction receives in total 4 bids, which are $10, $7, $5, and $2, respectively. Given these bids, how much is the total payment that the bidder who wins the second slot will pay?