https://www.luogu.org/discuss/show?postid=24360
 ![](https://cdn.luogu.com.cn/upload/pic/9072.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9073.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9074.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9075.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9076.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9077.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9078.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9079.png) 
 ![](https://cdn.luogu.com.cn/upload/pic/9080.png) 
![](https://cdn.luogu.com.cn/upload/pic/9081.png)