type 'a btree =
  Empty
| Leaf
| Node of ('a btree * 'a * 'a btree)

let rec add x t =
  match t with
  | Empty -> Leaf
  | Leaf -> Node(Leaf, x, Leaf)
  | Node (a, b, c) ->
     if x < b then
       Node(add x a, b, c)
     else if x >b then
       Node(a, b, add x c)
     else
       t
;;

Read_numbers_from_file.get_filename