let rec appendtolist l a =
  match l with
  |[] -> [a]
  |h :: t -> (h :: appendtolist t a)
;;

let take n words =
  let rec loop i l1 =
    if i = n
    then l1
    else
    if( n <= List.length words ) then
      loop (i + 1)  ( appendtolist l1 (List.nth words i) )
    else []
  in loop 0  []
;;