let () =
  let rec unique_element list =
    let rec _unique_element l s =  match l with
      | [] -> s
      | first :: rest ->
        if List.exists (fun e -> e = first) s then _unique_element rest s
        else _unique_element rest (s @ [first])
    in _unique_element list [] in
  let n = Scanf.scanf "%d\n" (fun x -> x) in
  let lst = Array.to_list (Array.init n (fun _ -> Scanf.scanf "%d " (fun x -> x))) in
  let slst = unique_element (List.fast_sort compare lst) in
  Printf.printf "%d\n"
    (if List.length slst < 2 then 0 
     else fst (List.fold_left 
        (fun (ans, bfr) x -> if abs(bfr - x) < ans then (abs(bfr - x), x) else (ans, x))
        (max_int, List.hd slst) (List.tl slst)))