open System

type NodeType = int
type Tree =
    | Nil
    | Node of NodeType * Tree * Tree

let createTree() =
    Node(1, Node(2, Node(4, Nil, Nil),
                    Node(5, Nil, Nil)),
            Node(3, Node(6, Nil, Nil),
                    Node(7, Node(9, Nil, Nil),
                            Node(8, Nil, Nil))
))

let rec inOrder visit tree =
    match tree with
    | Nil -> ()
    | Node(v, left, right) ->
        inOrder visit left
        visit v
        inOrder visit right

let mutable result = []
let sum v =
    result <- result @ [v]

let treeObj = createTree()
inOrder sum treeObj
Console.ReadLine() |> ignore