There are k square boxes of chocolate cubes. Each square box of size m contains m m cubes. The smallest box is size 1, the next one is size 2, ..., all the way up to size k. Boxes of odd size contain only dark chocolate cubes. Boxes of even size contain only milk chocolate cubes.

Design an algorithm to get the number of boxes k, then calculate the difference between the number of dark and milk chocolate cubes.