There are unicorns living in a magical kingdom on a plane.
People know the coordinates of $n$ points on the map: the places of unicorn sightings.

Recently, the king agreed to declare the territory inhabited by unicorns a nature reserve.
The boundaries of the reserve should be two parallel lines that will contain all $n$ places of unicorn sightings between them (or on them).
However, land in the kingdom is expensive, so the king does not want to allocate anything extra for the reserve: each boundary must pass through at least one of the $n$ points.

You are the chief ecologist of the kingdom.
Your task is to choose the boundaries of the reserve so that the king's will is fulfilled, but the reserve is as large as possible.
The size of the reserve is defined as the distance between the boundaries.
