let solve a_lst =
  let rec solve' lst result =
    match lst with
    | [] -> result
    | x::xs ->
      let result =
        match x with
        | n when n < 0 -> result - x
        | 0 | 1 -> result + x
        | _ -> result * x
      in
      solve' xs result
  in
  match a_lst with
  | x::xs -> solve' xs x
  | _ -> failwith "hoge"

let () =
  let _ = read_line ()
  and a_lst = read_line ()
              |> Str.split (Str.regexp_string " ")
              |> List.map int_of_string
  in
  solve a_lst
  |> string_of_int
  |> print_endline