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, _} -> m * :math.pow(p, 2)
      {_, 1} -> n * :math.pow(p, 2)
      _ -> 4 * :math.pow(p, 3)
    end +
      :math.pow(p, 4) *
        (if(n <= 2, do: 0, else: (n - 2) * 2) + if(m <= 2, do: 0, else: (m - 2) * 2)) +
      :math.pow(p, 5) * if n <= 2 || m <= 2, do: 0, else: (n - 2) * (m - 2)
  end
end