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.↵
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The address of the contest is [here](https://loj.ac/contest/21). Take part if you're willing to do some "exercise".↵
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I regret to say that the statements are provided in Mandarin. You can use google translate for translation if necessary.↵
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That's all. Thanks for your attention.↵
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**UPD**: I've completed the English version of the editorial. [Click here](https://loj.ac/article/306) to have a look.
↵
The address of the contest is [here](https://loj.ac/contest/21). 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](https://loj.ac/article/306) to have a look.