Turn on your mind and help the animals to cross the river! Everybody knows this famous puzzle - you should ferry animals over the river, but not all animals can be left with each other without keeping an eye on them. The boat can not go by itself. It needs someone to ride it. The cat can not travel with the dog. The mouse can not travel with the cat. The cat and the dog can not stay by themselves on the land. The cat and the mouse can not stay by themselves on the land.