let ``No.345 最小チワワ問題``() =
  
  let s = stdin.ReadLine()
  let Windexes =
    s
    |> Seq.mapi   (fun i c -> if c.Equals( 'w' ) then i + 1 else -1 )
    |> Seq.filter (fun i -> i >= 0)
    |> Seq.pairwise

  let res = 
    s
    |> Seq.mapi   (fun i c -> if c.Equals( 'c' ) then i else -1 )
    |> Seq.filter (fun i -> i >= 0)
    |> Seq.map ( fun n ->
        Windexes
        |> Seq.tryFind (fun (t1, t2) ->  n < t1 )
        |> function
          | Some (x1,x2)  -> x2 - n
          | None          -> -1
    )
  res
  |> Seq.max
  |> function
    | -1 -> -1
    |  _ -> res 
            |> Seq.filter( fun n -> n > 0)
            |> Seq.min
  |> stdout.WriteLine


``No.345 最小チワワ問題``()