100
A traveler comes to a fork in the road which leads to two villages. In one village the people always tell lies, and in the other village the people always tell the truth. The traveler needs to conduct business in the village where everyone tells the truth. A man from one of the villages is standing in the middle of the fork, but there is no indication of which village he is from. The traveler approaches the man and asks him one question. From the villager's answer, he knows which road to follow. What did the traveler ask?
The traveler asked "which road goes to your village". He would them take the road the villager pointed to because a truthful person would point towards the truthful village, and the liar would also point to the truthful village since he is a liar and, therefore, could not point to his own village.