Goodbye 2020. Hello 2021! <img src="/predownloaded/f4/1f/f41ff0beb745fb2f84a55d9f2cc451273efc6267.jpg" style="width:300px; float:right; margin: 0 1em 1em 1em"/> Hello Codeforces! This unusual and difficult 2020 has come to an end! What will the new year be like? I wish all of us that we have the opportunity to meet in person so that the contests take place not only online. I ask you to think of something important and good. Let this wish come true! We have had a large number of rounds this year. I hope we have pleased you with interesting problems. Thanks to the round coordinators and writers! You make our community richer. Please make us happy in 2021! I wish the participants victories over yourself (and over problems!) and development of your skills, interest and curiosity! Hello, 2021! And we have traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Only until the 10th of January, you can change your handle (<b>but only onc...

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Goodbye 2021. Hello 2022! <img src="/predownloaded/f4/1f/f41ff0beb745fb2f84a55d9f2cc451273efc6267.jpg" style="width:300px; float:right; margin: 0 1em 1em 1em"/> Hello Codeforces! Oh yes, 2021 ends! I recently realized that 2022 is pronounced like "2020 too". Not that. I want a completely different year! Anyway, we did a nice job this year. I hope we have pleased you with interesting problems. Thanks to the round coordinators and writers! You make our community richer. Please make us happy in 2022! I wish you all interesting tasks and brilliant solutions! I wish you error-free code and wish us only rated rounds :-) Hello, 2022! And we have traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for. You can change your han...

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Codeforces: summing up 2016 year <center> <img src="http://assets.codeforces.com/images/Happy-New-Year-HD-Wallpapers.jpg"/> </center> Somehow it turns out that for me, each coming the New Year means more and more. This is an excellent opportunity to take stock, to breathe fresh air and to go through a kind of catharsis. This is a rare opportunity to be with the family, dress up in Santa Claus and just have fun. Holidays give me a clear criterion that I do the right things. If during the holidays, I begin to think about it, to recall some deferred ideas, eager to implement something new. So I’m doing right things. My things. And now exactly the same as in several recent years: during New Year holidays I write code for Codeforces, trying new technology or simply I’m making minor changes in testlib. It is necessary to me: at this moment are no deadlines, do not press the obligation. Just now, at 3 am, I can not break away from being able to do something new. I would like to take a moment and realize that spun in ...

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Goodbye, 2025. Hello, 2026! <img src="/predownloaded/f4/1f/f41ff0beb745fb2f84a55d9f2cc451273efc6267.jpg" style="width:300px; float:right; margin: 0 1em 1em 1em"/> Goodbye, 2025. Hello, 2026! Dear Santa, Please make 2026 a happy year—not just for me, but for everyone. We all need this. Hello, 2026! And of course, we have our traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Until January 10, you can change your handle (<b>but only once</b>)! Note that next time you will be able to roll back the change or request another handle change only _after a year (in December 2026)_. Choose wisely! You can change your handle to a new one that hasn't been used by anyone else, or to one that you've previously used. Links to your old profile will automatically redirect to your updated profile. Again this year, if you've participated in at least 10 rounds, you can request the handle of an _inactive_ participant. This means the participant...

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Goodbye, 2024. Hello, 2025! <img src="/predownloaded/85/58/8558df7ac8a1c33d501ea8fd9b18dd3d95886b90.png" style="width:290px; float:right; margin: 0 1.5em 1.5em 1.5em"/> Goodbye, 2024. Hello, 2025! Dear Santa Claus, Please make 2025 a happy year—not just for me, but for everyone. We all need this. Hello, 2025! And of course, we have our traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Until the 10th of January, you can change your handle (<b>but only once</b>)! Note that you can roll back the changes or request another handle change only _after a year_. Choose wisely! You can change your handle to a new one that hasn’t been used by anyone else, or to one that you’ve previously used. Links to your old profile will automatically redirect to your updated profile. Again this year, if you’ve participated in at least 10 rounds, you can request the handle of an _inactive_ participant. This means the participant must have had a perio...

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Goodbye 2022. Hello 2023! <img src="/predownloaded/f4/1f/f41ff0beb745fb2f84a55d9f2cc451273efc6267.jpg" style="width:300px; float:right; margin: 0 1em 1em 1em"/> Dear Santa Claus. Please make 2023 a happy year, not just that. Please, we all need this. Hello, 2023! And we have traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for. You can change your handle to the new one which wasn't used before by anybody or which was used by you before. The links to a profile page with an old handle would automatically redirect to the actual profile. Again, this year if you took part in at least 10 rounds you can request a handle of an _inactive_ participant. It means that the participant should have a period of activity on Codeforces of...

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The holidays comes to us! Gifts! <img src="/predownloaded/d5/e7/d5e7e7554e5715c8088274efd5b40dee24e5cc18.png" style="float:right; margin: 0 1em 1em 1em;"/> Do you already have a New Year's mood? And we have traditional gifts! #### Change handle feature Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for. You can change your handle to the new one which wasn't used before by anybody or which was used by you before. The links to a profile page with old handle would automatically redirect to the actual profile. This year we have an improvement. If you took part in at least 10 rounds you can request handle of an _inactive_ participant. It means that the participant should have a period of activity on Codeforces of at most 30 days, this period should be in 2012 or earlier. The inactive participant can’t have posted comments, messages and s...

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Goodbye 2023. Hello 2024! <img src="/predownloaded/f4/1f/f41ff0beb745fb2f84a55d9f2cc451273efc6267.jpg" style="width:300px; float:right; margin: 0 1em 1em 1em"/> Dear Santa Claus. Please make 2024 a happy year, not just that. Please, we all need this. Hello, 2024! And we have traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for. You can change your handle to the new one that wasn't used before by anybody or which was used by you before. The links to a profile page with an old handle would automatically redirect to the actual profile. Again, this year if you took part in at least 10 rounds you can request a handle of an _inactive_ participant. It means that the participant should have a period of activity on Codeforces of ...

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New Year Gifts 2019! <img src="https://assets.codeforces.com/images/ny-meme.png" style="float:right; width:400px; margin: 0 1em 1em 1em;"/> Do you already have a New Year's mood? And we have traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for. You can change your handle to the new one which wasn't used before by anybody or which was used by you before. The links to a profile page with old handle would automatically redirect to the actual profile. This year we have an improvement. If you took part in at least 10 rounds you can request handle of an _inactive_ participant. It means that the participant should have a period of activity on Codeforces of at most 90 days, this period should be in 2015 or earlier. The inacti...

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Statistics of New Year Magic #### Introduction New Year's traditional masquerade of colors and ranks is going to end pretty soon, and before it goes away, I decided to download a snapshot of everyone's true ratings and current handle colors to see how everyone's using the feature. I regret that I only have one snapshot; I only managed to push myself to finish this today. It would have been really cool to see how people's usage of the feature has evolved &mdash; perhaps an initial surge of masquerading as a nutella, then slowly coming to one's senses and opting for something milder? Data was collected on January 9th, at about 01:00 UTC. I collected the data by scraping the pages of the "rating" tab (sorry for making a lot of requests!) &mdash; the table contains people's actual ratings, and by looking at the title-text of people's handles, I could also get their possibly-magicked ranks. I only included the active people because it was already taking a lot of time, and I believe we got most of the interesting ...

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New Year Gifts 2020! <img src="https://assets.codeforces.com/images/ny-meme.png" style="float:right; width:400px; margin: 0 1em 1em 1em;"/> Do you already have a New Year's mood? And we have traditional gifts! #### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for. You can change your handle to the new one which wasn't used before by anybody or which was used by you before. The links to a profile page with an old handle would automatically redirect to the actual profile. Again, this year if you took part in at least 10 rounds you can request a handle of an _inactive_ participant. It means that the participant should have a period of activity on Codeforces of at most 180 days, this period should be in 2016 or earlier. The inactive participa...

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Antimagic Hello everyone! Since the masquerade of colors and ranks was announced, many pseudo-creative shitblogs from pseudo-nutellas will appear soon. Of course, some of them may be [funny](https://codeforces.me/blog/entry/15511) (especially when it's not about newbies trying to look smarter but vice versa), but one can be sick about all this situation. Usually it's not funny, but annoying. This is why I decided to create a script which would reveal the true colors and titles. I think it does not (completely) kill the idea of changing colors: if one wants to take part in this masquerade, they can ignore my post and will still see the colors chosen by others (including their own) instead of the true ones. This extension _extends_ the page loading time because it downloads a ~1.6mb file. It shouldn't change the title on the profile page, but what it should do is make all in-page colors look properly. It also doesn't change the site background since killing the new year spirit is not wha...

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Gandalf meets Saruman scene In recent times, the platform of Codeforces has been besieged by a tempest of indignation and discourse surrounding the topic of cheating. Yet amid the chaos and moral reckonings, there has emerged an unexpected artifact — a piece of sublime satire: [link](https://www.youtube.com/watch?v=1Z4BF3AkeMQ&ab_channel=SamvelAndreasyan). This is a satirical reinterpretation masquerading as a classical masterpiece. Every frame is soaked in irony, crafted with an exaggerated seriousness that pokes fun at its own grandeur. Take nothing at face value—this is parody in its most noble form. Once misunderstood, this magnum opus has since been dissected by critics who now argue that the “friend” referenced throughout is not a human companion but rather a Codeforces friend. The final, chilling utterance of “friend” by Gandalf is now widely interpreted as the climactic revocation of the star.

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Please replace instances of O(n^1/e) with $O(dmax(n))$ in divisor counting problems Please respect the function $dmax(n)$ by actually using it, instead of masquerading it for a random function that serves as a **very rough** approximation. Context: $dmax(n)$ is $max_{1\leq i \leq n}\tau(n)$. <spoiler summary="Fact"> $1/e \geq 1/3$. </spoiler>

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Correlation between magic rank and actual rank I notice something quite interesting. The higher ranked people generally use magic to make themselves low ranked (such as cyan which is a very popular low ranked colour for some reason). [user:um_nik,2022-12-29] is one good example. On the other hand, we have real greys, greens, cyans and blue masquerading as as LGM or reds. I find this very fascinating and am able to conclude something. The lower your ranking, the more you feel you should higher ranked. Yet once u are at the top (like those LGMs), you think you are not that good and should be newbie instead. What do you guys think?

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Problems in the NOI Dictionary Typical Topic Sets (CSP-S ~ Provincial Team Selection) Some topics / knowledge that are too basic will not be added This problem set has some good problems corresponding to the knowledge, and you can add a sentence on this topic to give a brief description of the practice as appropriate. Since I haven't solved all the problems, if someone can provide it, please contact [gsczl71](/profile/gsczl71 "Expert gsczl71") on Codeforces If you want to add some better problems for some knowledge, you can contact me and add them. A '\*' will be added in front of the problem number. ## Improvement ### 2.3.1.4 Priority queues - [P6033 [NOIP2004 Improvement Group] Merging Fruit Enhancement](https://www.luogu.com.cn/problem/P6033) - [P2827 [NOIP2016 Improvement Group] Earthworms](https://www.luogu.com.cn/problem/P2827) - [P3045 [USACO12FEB] Cow Coupons G](https://www.luogu.com.cn/problem/P3045) ### 2.3.1.5 Sparse Table - [P2048 [NOI2010] Super Piano](https://www.luogu.com.cn/proble...

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