open System
open System.Text.RegularExpressions

let pattern = new Regex(@"c.*?w.*?w")
let searchCww (str:string) =
    seq { for i in 0..(str.Length - 3) -> pattern.Match(str, i) } |>
    Seq.choose (function m when m.Success -> Some m.Length | _ -> None) |>
    (fun s -> if Seq.isEmpty s then -1 else Seq.min s)

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