in：

8
1 
2 
3 
4 
1 
2
3 
4 

out：

4

but：

---

https://wangziminghedan.blog.luogu.org/p3146-usaco16open248-ti-xie 输出0

https://www.luogu.com.cn/blog/user18170/solution-p3146 输出5

https://www.luogu.com.cn/blog/expect2004/solution-p3146 输出5

https://www.luogu.com.cn/blog/134080/solution-p3146 输出5

https://239030.blog.luogu.org/solution-p3146 输出0

https://www.luogu.com.cn/blog/ClHg2/solution-p3146 输出5

https://www.luogu.com.cn/blog/Tony102/solution-p3146 输出5

https://www.luogu.com.cn/blog/isecloud/solution-p3146 输出5

https://www.luogu.com.cn/blog/henry-y/solution-p3146 没有输出

https://www.luogu.com.cn/blog/user9012/solution-p3146 输出5

https://www.luogu.com.cn/blog/xyuren/solution-p3146 输出0

https://www.luogu.com.cn/blog/ctq1999/solution-p3146 输出5

https://151720.blog.luogu.org/solution-p3146 输出5

https://www.luogu.com.cn/blog/yosowang/solution-p3146 输出5

https://www.luogu.com.cn/blog/Manjusaka/solution-p3146 输出5