Do you know second-price auction? It's very simple but famous. In a second-price auction, each potential buyer privately submits, perhaps in a sealed envelope or over a secure connection, his (or her) bid for the object to the auctioneer. After receiving all the bids, the auctioneer then awards the object to the bidder with the highest bid, and charges him (or her) the amount of the second-highest bid.
Suppose you're the auctioneer and you have received all the bids, you should decide the winner and the amount of money he (or she) should pay.
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