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.io.*;
import java.util.*;

public class FillingShapes{

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());

        if(n==1){
            System.out.println(0);
            return;
        }

        long res[] = new long[n];
        res[0] = 0;
        res[1] = 2;
        for(int i=2;i<n;i++){
            res[i] = res[i-2]*2;
        }

        System.out.println(res[n-1]);
    }
}