in:

9 12
1 7 8 9
1 2 1
2 5 1
2 3 1
2 6 1
3 4 1
5 4 1
4 7 1
4 6 1
8 5 1
5 3 1
3 6 1
6 9 1

out:

1

本题21篇题解中,以下15篇题解均输出2:

1. https://www.luogu.com.cn/blog/chdy/solution-p2149

2. https://www.luogu.com.cn/blog/Atalod/solution-p2149

3. https://www.luogu.com.cn/blog/FrigidPigeon/solution-p2149

4. https://www.luogu.com.cn/blog/pleasun/p2149-sdoi2009elaxia-di-lu-xian-ti-xie

5. https://www.luogu.com.cn/blog/DanKuroto/solution-p2109

6. https://www.luogu.com.cn/blog/user11280/solution-p2149

7. https://www.luogu.com.cn/blog/wqt1600639146/luo-gu-2149-zui-zhang-gong-gong-lu-jing-post

8. https://www.luogu.com.cn/blog/xxwang/elaxia-di-lu-xian

9. https://thisworld.blog.luogu.org/solution-p2149

10. https://www.luogu.com.cn/blog/mlystdcall/solution-p2149

11. https://www.luogu.com.cn/blog/user29936/solution-p2149

12. https://wyx.blog.luogu.org/solution-p2149

13. https://www.luogu.com.cn/blog/XTZORZ/solution-p2149

14. https://www.luogu.com.cn/blog/lemonyali/solution-p2149

15. https://www.luogu.com.cn/blog/skylee/solution-p2149