Filling Shapes

Description:
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.

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.

Code:

#include <bits/stdc++.h>
using namespace std;
int main()
{
long long n;
cin >> n;
if (n % 2 != 0)
cout << 0 << endl;
else
{
n /= 2;
n  = pow(2, n);
printf("%lld\n", n);
}
return 0;
}


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