You are familiar with river crossing problems I'm sure. You know: A man has to cross a river with a wolf, a goat and a cabbage. He has access to a small row boat, but he only has room for himself and one other item (either the wolf, the goat or the cabbage). But he must not leave the wolf and the goat alone together on one side of the river or the wolf will eat the goat. He also cannot leave the goat alone with the cabbage, because the goat will eat the cabbage.
A student told me the shortest and most efficient solution to this problem. First, the man takes the goat to the other side of the river, and then rows back alone. Then he takes the cabbage to the other side of the river. Now he's done.
But what about the wolf? Who needs a wolf, they are dangerous and can kill you! Leave the wolf behind!