Problem:
Score : 200 points

Problem Statement

We will say that two integer sequences of length N, x_1, x_2, ..., x_N and y_1, y_2, ..., y_N, are similar when |x_i - y_i| \leq 1 holds for all i (1 \leq i \leq N).

In particular, any integer sequence is similar to itself.

You are given an integer N and an integer sequence of length N, A_1, A_2, ..., A_N.

How many integer sequences b_1, b_2, ..., b_N are there such that b_1, b_2, ..., b_N is similar to A and the product of all elements, b_1 b_2 ... b_N, is even?

Constraints

1 \leq N \leq 10

1 \leq A_i \leq 100

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the number of integer sequences that satisfy the condition.

Sample Input 1

2
2 3

Sample Output 1

7

There are seven integer sequences that satisfy the condition:

1, 2

1, 4

2, 2

2, 3

2, 4

3, 2

3, 4

Sample Input 2

3
3 3 3

Sample Output 2

26

Sample Input 3

1
100

Sample Output 3

1

Sample Input 4

10
90 52 56 71 44 8 13 30 57 84

Sample Output 4

58921

Solution in OCaml (4.02.3) (judge verdict: Accepted)

open Printf
open Scanf

let () =
  let n = scanf "%d " (fun x -> x) in
  let rec read i =
    if i = 0 then []
    else let v = scanf "%d " (fun x -> x) in
         v :: read (i - 1) in
  let ls = read n in
  let rec expt3 n =
    if n = 0 then 1 else 3 * (expt3 (n - 1)) in
  expt3 n - (List.fold_left (fun a x -> if x mod 2 = 0 then a * 2 else a) 1 ls) |> printf "%d\n"