Conundrum Sphinx

First the player whose turn it is names a card, then each other player in turn order does the same. Then each player reveals the top card of their library at the same time.

If a card a player reveals this way is the card that particular player named, they must put it into their hand. Otherwise, they must put it on the bottom of their library, even if it’s the card a different player named. In no cases can a player leave the revealed card on top of their library.