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

  def solve(s) do
    t = [
      s |> String.length()
      | Regex.scan(~r/(?=(c[^cw]*?w[^w]*?w))/, s)
        |> Enum.map(fn [_, x] -> x |> String.length() end)
    ]

    cond do
      t |> length == 1 -> -1
      true -> t |> Enum.min()
    end
  end
end