So you take hike to look for a tribe that is known to always tell the truth. You reach a fork in the trail. One trail leads to the tribe that always tells the truth, while the other leads to the tribe that always lies. There is a man standing right at the fork. He's from one of the tribes, but you can't tell which. You can ask him one question only.
What do you ask him in order to take the trail that leads to the tribe that always tells the truth?