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Time Limit: 1 s Memory Limit: 128 MB Total points: 100

#17436. 连接点

Statistics

考虑一个 $3 \times N$ 的规则点阵。点阵中的每个点最多有八个相邻的点(见图 1)。

图 1:相邻的点(用箭头标出)

我们希望计算有多少种不同的方法来连接点阵中的点,以形成一个满足以下条件的多边形:

  • 多边形的顶点集由所有 $3 \times N$ 个点组成。
  • 多边形中相邻的顶点在点阵中也是相邻的点。
  • 每个多边形都是简单多边形,即不能有任何自交。

图 2 给出了 $N = 6$ 时两种可能的连接方式。

图 2:$N = 6$ 时两种可能的连接方式

编写一个程序,对于给定的 $N$,计算满足上述要求的连接方法的总数模 $1,000,000,000$ 的余数。

输入格式

输入只有一行,包含一个正整数 $N$($N \le 1,000,000,000$)。

输出格式

输出只有一行,包含连接点阵中点的可行方法数模 $1,000,000,000$ 的余数。

样例

输入样例 1

3

输出样例 1

8

输入样例 2

4

输出样例 2

40

子任务

  • $30\%$ 的测试数据满足 $N \le 200$。
  • $70\%$ 的测试数据满足 $N \le 100,000$。

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