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.
def main():
    n=int(input())
    dp=[]
    dp.append(0)
    dp.append(0)
    dp.append(2)
    for i in range(3,n+1):
        dp.append(dp[i-2]*2)
    print(dp[n])
if __name__=="__main__":
    main()