module Stack =
    let pop = function
    | x::xs -> Some(x), xs
    | [] -> None, []

    let push l x = x::l

    let head list =
        match List.length l with
        | 0 -> None
        | _ -> Some(l.[0])

    let size l = List.length l


module Queue =
    let pop = function
    | x::xs -> Some(x), xs
    | [] -> None, []

    let push l x = l @ [x]

    let head list =
        match List.length l with
        | 0 -> None
        | _ -> Some(l.[0])

    let size l = List.length l


module Program =
    let rec addall st = function
        | 10 -> st
        | x -> addall (Stack.push st x) (x + 1)

    let rec printall st =
        let a, nst = Stack.pop st
        match a with
        | None -> None
        | Some(x) ->
            printf "%d " x
            printall nst

    [<EntryPoint>]
    let main argv =


        let st = addall [] 0
        printall st
        0 // return an integer exit code