【题解】A. Filling Shapes⭐ 【水题】

A. Filling Shapes

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

inputCopy
4
outputCopy
4
inputCopy
1
outputCopy
0

Hint

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

In the second example, you cannot fill the shapes in 3×1 tiles.

题意:

用左边的图形填充一个3*N的矩形, 问有多少种不同的填充方案

题解:

简单的数学计数问题

经验小结:

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
#define ms(x, n) memset(x,n,sizeof(x));
typedef  long long LL;
const int inf = 1<<30;
const LL maxn = 1e5+10;

int main()
{
    int n;
    cin >> n;
    if(n%2 == 1) cout << "0" << endl;
    else cout << (1<<(n/2)) << endl;

	return 0;
}