defmodule Main do
  def main do
    [n, m] =
      IO.read(:line)
      |> String.trim()
      |> String.split()
      |> Enum.map(&String.to_integer/1)

    p =
      IO.read(:line)
      |> String.trim()
      |> (fn s ->
            case s do
              "0" -> 0
              "1" -> 1
              _ -> s |> String.to_float()
            end
          end).()

    solve({n, m}, p)
    |> IO.puts()
  end

  def solve({n, m}, p) do
    case {n, m} do
      {1, 1} ->
        p

      {1, 2} ->
        2 * :math.pow(p, 2)

      {1, _} ->
        m * :math.pow(p, 2) + :math.pow(p, 3) * (m - 2)

      {2, 1} ->
        2 * :math.pow(p, 2)

      {_, 1} ->
        n * :math.pow(p, 2) + :math.pow(p, 3) * (n - 2)

      _ ->
        4 * :math.pow(p, 3) + :math.pow(p, 4) * (2 * n + 2 * m - 8) +
          :math.pow(p, 5) * (n - 2) * (m - 2)
    end
  end
end