defmodule MSrt do
  def mSrt([]), do: []
  def mSrt([e]), do: [e]
  def mSrt(ls) do
    hf=div(length(ls),2)
    {l1,l2}=Enum.split(ls,hf)
    mMrg(mSrt(l1),mSrt(l2))
  end
  defp mMrg([],ls), do: ls
  defp mMrg(ls,[]), do: ls
  defp mMrg([e1,r1],[e2,r2]) when e1>e2, do:
    [e1|mMrg(r1,[e2|r2])]
  defp mMrg(l1,[e2|r2]), do: [e2|mMrg(l1,r2)]
end