input: Write a python function to calculate the number of smaller cubes of size k contained within a larger cube of size n.
  assert count_smaller_cubes(2,1) == 8
  assert count_smaller_cubes(5,2) == 64
  assert count_smaller_cubes(1,1) == 1
output: def count_smaller_cubes(n, k):
      return (n // k) ** 3