open System

// prelude
let readStr () = stdin.ReadLine()

let read f () = readStr() |> f
let reads f () = readStr().Split() |> Array.map f

let pair = function
| [|a; b|] -> (a, b)
| _ -> failwith "owatta"

let triple = function
| [|a; b; c|] -> (a, b, c)
| _ -> failwith "owatta"

let readPair f g () =
  let (a,b) = readStr().Split() |> pair
  (f a, g b)

let readTriple f g h () =
  let (a,b,c) = readStr().Split() |> triple
  (f a, g b, h c)

let inc n = n + 1
let dec n = n - 1

let inline flip f a b = f b a
let rec fix f = fun x -> (f (fix f)) x

module Option =
  let getOr defaultValue = function
  | Some x -> x
  | None -> defaultValue

module Array =
  let modify (arr: _ []) i f =
    arr.[i] <- f arr.[i]

module Array2D =
  let modify (arr: _ [,]) i j f =
    arr.[i, j] <- f arr.[i, j]

// start
readStr()

let A = reads int64 ()
if A |> Array.exists ((=) 0L) then do
  printfn "0"
  exit 0
let MAX = int64 (1e18)
A
|> Array.fold (
  fun st x ->
    match st with
    | Some s ->
      let y = s*x
      if y>MAX then None else Some y
    | None -> None
) (Some 1L)
|> function
| Some x -> x
| None -> -1L
|> printfn "%d"