Wanish playing

About Wanish, from BoardGameGeek:

The game purpose is to collect five different crocodiles. The game starts with 20 playing pieces placed face down, then each player takes 5 pieces and keeps them hidden from the opponent. During the game you will be exchanging your pieces for the pieces on the table or your opponent's pieces, or showing your pieces. The game consists of four matches. The match ends when you show five different crocodiles, and you get 5 points minus a point for each pair.