UVA12371 守卫 Guards

Description

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=278&page=show_problem&problem=3793 [PDF](https://uva.onlinejudge.org/external/123/p12371.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12371/56ee60e1086545cf623517834e542f3eaaf7395e.png)

Input Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12371/f590bff37eccfd49c7a808730469fefe6ad6f794.png)

Output Format

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA12371/23dec68c665cce3888f3d8e927439649e18f3f6f.png)