defmodule Main do
  def main do
    IO.read(:line)
    |> String.trim()
    |> String.to_integer()
    |> solve()
    |> IO.puts()
  end

  def calc_count(i) do
    {i,
     for(j <- 1..(:math.sqrt(i) |> floor), rem(i, j) == 0, do: if(j == div(i, j), do: 1, else: 2))
     |> Enum.sum()}
  end

  def solve(n) do
    1..n
    |> Enum.map(&calc_count/1)
    |> Enum.reduce(0, fn {k, f}, acc -> acc + k * f end)
  end

  def pmap(n) do
    me = self()

    1..n
    |> Enum.map(fn i -> spawn_link(fn -> send(me, {self(), calc_count(i)}) end) end)
    |> Enum.map(fn _pid ->
      receive do
        {_, {k, f}} ->
          k * f
      end
    end)
    |> Enum.sum()
  end
end