I am on an island.
On the island, there are two tribes.
The first tribe is called normal tribe. They always tell the truth.
The other tribe is called monster tribe. They always lie.
The normal tribe lives in the "normal village". The moster tribe lives in the "monster village".
Any non-residents who appeared in the monster village will be eaten by the monster tribe! (Hence the name of the tribe...... )
If you meet any human on the island, just by looking at their apperances, no one can tell which tribe he/she belongs to.
Because of some important business, I need to go to "normal village".
I walked along a road, and I realized I am on a "T-junction"; in front of me there are two roads, one leading to the east and one leading to the west.
I know that one of the roads will lead me to "normal village", where the other would lead me to "monster village" - that means road to death!
I don't know which road to choose. However, right at the T-junction, there is a person. I do not know where he comes from, but he must come from "normal village" or "monster village".
I have no choice but to consult this person, who may or may not tell the truth.
If I am only allowed to ask him one question, how should I ask in order to find the way to "normal village"?