CF280D

$luogu-CF280D$

CSP-S 2020前我就想把这道题写出来，但是迫于能力，debug无果。

I wanted to write this question before CSP-S 2020, but due to ability, debug was fruitless.

现在我想要持续的debug这道题，再也不放弃了！

Now I want to continue the debug problem, never give up again!

Log

202011132301

还在写$upd$，$149lines$

202011181605

咕了几天之后，刚刚随便打了一会儿。已经全部打完了，开始$debug$...$291lines$。