Scanf.scanf "%s" (fun s ->
    let n = String.length s in
    let rec loop i x y =
        if i = n then sqrt (float (x * x + y * y)) else
            match s.[i] with
            | 'N' -> loop (i + 1) x (y + 1)
            | 'S' -> loop (i + 1) x (y - 1)
            | 'E' -> loop (i + 1) (x + 1) y
            | 'W' -> loop (i + 1) (x - 1) y
            | _ -> failwith "??"
    in
    loop 0 0 0 |> Printf.printf "%f\n"
)