open System
open System.Text.RegularExpressions

let pattern = new Regex(@"c.*?w.*?w")
let searchCww str =
    pattern.Matches(str) |>
    function m when m.Count = 0 -> -1
           | m -> seq { 0..(str.Length - 3) } |>
                  Seq.map (fun i -> pattern.Match(str, i)) |>
                  Seq.choose (function m when m.Success -> Some m.Length | _ -> None) |>
                  Seq.min

Console.ReadLine () |> searchCww |> printfn "%d"