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

  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) ->  t1 > n )
      |> function
        | Some (x1,x2)  -> x2 - n
        | None          -> -1
  )
  |> Seq.min
  |> stdout.WriteLine

``No.345 最小チワワ問題``()