Problem:
Score : 200 points

Problem Statement

Given N integers A_1, ..., A_N, compute A_1 \times ... \times A_N.

However, if the result exceeds 10^{18}, print -1 instead.

Constraints

2 \leq N \leq 10^5

0 \leq A_i \leq 10^{18}

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 ... A_N

Output

Print the value A_1 \times ... \times A_N as an integer, or -1 if the value exceeds 10^{18}.

Sample Input 1

2
1000000000 1000000000

Sample Output 1

1000000000000000000

We have 1000000000 \times 1000000000 = 1000000000000000000.

Sample Input 2

3
101 9901 999999000001

Sample Output 2

-1

We have 101 \times 9901 \times 999999000001 = 1000000000000000001, which exceeds 10^{18}, so we should print -1 instead.

Sample Input 3

31
4 1 5 9 2 6 5 3 5 8 9 7 9 3 2 3 8 4 6 2 6 4 3 3 8 3 2 7 9 5 0

Sample Output 3

0

Solution in OCaml (4.10.0) (judge verdict: Accepted)

(*
ocamlfind ocamlopt -package batteries -linkpkg main.ml -o a.out
*)
open Batteries

let n = Scanf.sscanf (read_line ()) "%d" ( fun n -> n)

let lst = Str.split (Str.regexp " ") (read_line ())
          |> List.map int_of_string 

let rec log2 n =
        if n = 0 then
                0
        else
                1 + (log2 (n lsr 1))

let rec f lst ac =
        if ac > (Int.pow 10 18) then
                -1
        else
                match lst with
                          [] -> ac
                        | first :: rest -> 
                                let bac = (log2 ac) - 1 in
                                let bfst = log2 first in
                                        if (bac + bfst) > 60 then
                                                -1
                                        else
                                                f rest (ac * first)

let () =
        (
                if List.exists (fun elmnt -> elmnt = 0) lst then
                        0
                else
                        f lst 1
        ) |> Printf.printf "%d\n"