Filling Shapes

Link: CodeForces-566-A
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;
}

Nothing to say,just find the regular,and cout is something wrong happen and I don’t know the reason now.Record it here!