defmodule Main do
  defp prime?(n) do
    case n do
      1 -> false
      2 -> true
      _ -> Enum.all?(2..(n - 1), &(rem(n, &1) != 0))
    end
  end

  def main do
    n = IO.gets("") |> String.trim |> String.to_integer

    ans = 1..n |> Enum.filter(&prime?/1) |> Enum.sum

    IO.puts ans
  end
end