You have a given integer n. Find the number of ways to fill all 3 × n tiles with the shape described in the picture below. Upon filling, no empty spaces are allowed. Shapes cannot overlap.

<image> This picture describes when n = 4. The left one is the shape and the right one is 3 × n tiles. 

Input

The only line contains one integer n (1 ≤ n ≤ 60) — the length.

Output

Print the number of ways to fill.

Examples

Input


4


Output


4

Input


1


Output


0

Note

In the first example, there are 4 possible cases of filling.

In the second example, you cannot fill the shapes in 3 × 1 tiles.
import java.util.*;
public class A1182 {
    static int [] mem;
    public static void main(String [] args){
        Scanner scan = new Scanner(System.in);
        int n = Integer.parseInt(scan.nextLine());

        mem = new int [n+1];
        for(int i = 0; i < n; i++){
            mem[i] = -1;
        }
        mem[0] = 0;
        mem[1] = 2;
        System.out.println(dp(n-1));
    }
    public static int dp(int k){
       if(mem[k] == -1)
           return 2* dp(k-2);
       return mem[k];
    }
}
