You are lost in the woods and the path you are following forks into two: a path to the left and one to the right. One path will lead you to safety while the other will cause you to be lost forever.
At the fork are two twin sisters who know which path is which. The sisters are identical in every way except one: one of the sisters always tells the truth while the other always lies.
You can ask only one question and you don’t know which sister is which. What can you say to them so you know which path to take?