I'm sorry to have delayed posting this entry for about an hour, and that Codeforces Round #464(Div.2) is beginning soon after this contest.

The address of the contest is here. Take part if you're willing to do some "exercise".

I regret to say that the statements are provided in Mandarin. You can use google translate for translation if necessary.

That's all. Thanks for your attention.

UPD: I've completed the English version of the editorial. Click here to have a look.