let ``No.289 数字を全て足そう`` () =
    stdin.ReadLine()
    |> Seq.choose (fun c ->
        let n = int c
        if 48 <= n && n <= 57 then Some (n-48)
        else None)
    |> Seq.sum
    |> (printfn "%d")
``No.289 数字を全て足そう`` ()