A road is divided into two ways of which one leads to City of truth and other leads to City of Lies. Citizens of the City of Lies always lie. Citizens of the City of Truth always tell the truth.
There are two people standing at division one from City of Truth and other from City of Lies. You don’t know who belongs to which city. You can ask only one question from any of the two people standing there to find which way leads to the city of truth and which leads to the city of lies.
Ask anyone, “Which city do you belong too?”
In this case, the person belonging to the City of Truth always tell the truth and will tell you the way to his city, while the person belonging to City of Lies will lie and point in the direction of the City of Truth.