What is the minimum number of circles with radius r needed to cover all n points?
r and n will be given as input, followed by n pairs of integers representing the x-y co-ordinates of the n points.
r is a real number and greater than 0. n is < 20.

A circle covers a point if the point lies inside the circle.
A point lies inside a circle if the distance between the point and the center of the circle is less than or equal to r.