UVA12556 "Center" of perimeter midpoints

Description

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=441&page=show_problem&problem=4001 [PDF](https://uva.onlinejudge.org/external/125/p12556.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12556/288b565b05501e59e81b72bf0b14b13abb1fb0b0.png)

Input Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12556/019f1ca33c36baa8347b392e694a6f0ec1464126.png)

Output Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12556/687a3b8846eaf1f7afde31bd69cfef547cfea966.png)