BitByBit123's blog

Suspicious Master yql0991666
By BitByBit123, 4 weeks ago, In English

Update on 8/18/2026: yql0991666 have cheated to become a Master. How can he still not be banned?

Update: Congratulations to yql0991666, the CHEATER is disabled! Good job, Mike!

I, BitByBit123, suspect that yql0991666 is a cheater. I would like to report some suspicious behaviors and request an investigation.

Update on 8/18/2026

yql0991666, could you explain 387437964 387437988 how can you write 1.6KB code in 3 seconds?

Looking at the code for Problem E, what kind of person would write such a long definition on a single line (the fourth line)?

If you interpret this as a way to make the code more compact (by consolidating lines), then why are the assignment statements on lines 19 through 24 separated?

The only explanation is that the AI-generated code was partially modified.

Also yql0991666 you didn't solve problem D because you allocated an array smaller than required, Even when there's a notification saying the data range changed. The only explanation is that yql0991666 can't read English and copied the wrong statement to ChatGPT.

And yql0991666 you use indention with a tab size 4 before but 8 now, WHY??

Also lets check out his weird code.

Suspicious contest behavior

As shown above, yql0991666 solved multiple problems in an unusually short period of time and in an unusual order. Some other examples:

https://codeforces.me/contest/2252/submission/385960817

https://codeforces.me/contest/2252/submission/385961550

During contests, the user submitted multiple accepted solutions for the same problem, where the only visible changes were formatting-related (such as spaces or indentation).

AI-like code style and inconsistent coding habits

Examples:

https://codeforces.me/contest/2253/submission/386124818

https://codeforces.me/contest/2248/submission/385185432

https://codeforces.me/contest/2252/submission/385961550

Some submissions contain coding patterns that are commonly seen in AI-generated code, for example:

if(cin>>T)
{
    while(T--)
    {
        /* ... */
    }
}

and:

if(!(cin>>n))return 0;

These patterns appear in some of the user's submissions but not in others, indicating a significant inconsistency in coding style.

Additional inconsistencies include:

  • Mixing int* and int[] styles in function parameters.
  • Mixing spaces and tabs for indentation.

Examples:

https://codeforces.me/contest/2253/submission/386124818

https://codeforces.me/contest/2253/submission/386109857

https://codeforces.me/contest/2253/submission/386124802

I understand that coding style alone cannot prove cheating, but these changes may indicate that some submissions were not written in the user's usual style.

Inconsistent performance

yql0991666 previously had performances around the 10000+ rank range, but recently achieved several extremely high placements, including top 50 finishes, with a rapid rating increase.

Relevant information:

The improvement appears to be significantly inconsistent with the user's previous competitive programming history.

Additionally, according to publicly available records, yql0991666 scored 100 points in CSP-J2024 and 130 points in CSP-J2025. These results suggest that he can hardly solve problems with difficulty higher than *800 or *1000, which appears inconsistent with the user's recent Codeforces performance.

Source:

Additional information

I personally know this user, Yin Qilong, from the Chinese OI community. There have been previous controversies involving this user, including alleged cheating and harassment on other platforms such as Luogu.

I understand that these points alone may not conclusively prove cheating, so I would appreciate it if Codeforces staff could review the account and related submissions.

(By the way, it has been a long time since the last rollback and there're a lot of cheaters in the latest contests, so could we have a rollback?)

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4 weeks ago, hide # |
 
Vote: I like it +71 Vote: I do not like it

I have heard a bit about yql0991666. In my opinion, he does not have the strength to get such results in the contest, and his submission patterns are highly questionable. I consider him a cheater.

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Vote: I like it +79 Vote: I do not like it

image

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4 weeks ago, hide # |
← Rev. 2  
Vote: I like it +61 Vote: I do not like it

MikeMirzayanov Vladosiya

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4 weeks ago, hide # |
 
Vote: I like it +103 Vote: I do not like it

The person has two Luogu accounts: the first one (yql0991666) was banned, and the second one (__yql0991888__) was a cheater and received a brown tag

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4 weeks ago, hide # |
 
Vote: I like it +72 Vote: I do not like it

“Additionally, according to publicly available records, yql0991666 scored 100 points in CSP-J2024 and 130 points in CSP-J2025. These results suggest that he can hardly solve problems with difficulty higher than *800 or *1000, which appears inconsistent with the user's recent Codeforces performance.”

I also don't think his level in domestic competitions(i.e., CSP-J) can reach the standard of solving three problems in a Codeforces Div. 1 round.

*ps. CSP-J has 4 problems with rating *800~1200, *800~1200, *1300~1400 and *1500~1700. I'm not sure if he's capable of solving an 800-level problem on Codeforces.

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4 weeks ago, hide # |
 
Vote: I like it +35 Vote: I do not like it

Ban that cheater pls. I don't wanna see crazy cheaters like that anymore.

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Vote: I like it -51 Vote: I do not like it

Don't downvote me please. wo shi chuan zi.

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4 weeks ago, hide # |
 
Vote: I like it +52 Vote: I do not like it

More and more cheaters who should be punished. When rollback?

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4 weeks ago, hide # |
 
Vote: I like it -22 Vote: I do not like it

No ma I le, I shi yin qi dragon.

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Vote: I like it -15 Vote: I do not like it

rk++

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4 weeks ago, hide # |
 
Vote: I like it +37 Vote: I do not like it

I strongly support banning yql0991666.

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4 weeks ago, hide # |
 
Vote: I like it +22 Vote: I do not like it

There is ample evidence to support this report, and I don’t believe all of the above is just a coincidence.

Supplement‌:

What's more, he even used both tabs and spaces for indentation in a single block of code (even in a single line)! This is highly unlikely to happen if he wrote the code manually in an editor. I believe he modified this AI-generated code.

Evidence:

Note: a little round dot represents a space while a arrow represents a tab in the picture(in the view of Microsoft VS Code).

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4 weeks ago, hide # |
 
Vote: I like it +9 Vote: I do not like it

cause dragon is so strong !!1

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4 weeks ago, hide # |
 
Vote: I like it +51 Vote: I do not like it

There are more and more cheaters in div2, and even div1.

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4 weeks ago, hide # |
 
Vote: I like it +32 Vote: I do not like it

His Luogu(Chinese OJ) accounts:

Account1(Banned)

Account2(has been flagged as a cheater)

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4 weeks ago, hide # |
 
Vote: I like it +24 Vote: I do not like it

"Honestly, a rollback isn't enough at this point. We need a new 'Skip to Ban' button for accounts with a rating graph that looks like a SpaceX rocket launch.

Excellent investigation, BitByBit123!"

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4 weeks ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

I used to think, that no one will cheat in div 1. because only legitimate people can get there bcz of hardness of questions. but I was wrong. cheaters even cheating in div 1.

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4 weeks ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

The Codeforces Div-2 lobby is so bad that even after solving A, B, C, people end at 1200 rating due to such cheaters, there are so many like him

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4 weeks ago, hide # |
 
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Oh yet another cheater. And I bet there's a lot more. What the hell is the point? I don't get why they ever wanna cheat.

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he even changed the AI's coding style to hide that he was cheating

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4 weeks ago, hide # |
 
Vote: I like it +18 Vote: I do not like it

Say dian something big home don't know, I am is Cause Dragon. I am is a gay. Big god no kill me, no kill me, I have no money.

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    4 weeks ago, hide # ^ |
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    If you keep such speaking way, I will teach you how to speak English with my big red sausage.

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    Oh,bro.you English are very bad,I think I need to immediately go to your computer room and educate you on English.Like zak all kill IOI.

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      4 weeks ago, hide # ^ |
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      666 怎么都给我 downvote，是不是都嘲讽我英语不好？那我就直说了，我语文也不好。

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        4 weeks ago, hide # ^ |
         
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        Oh,You are clever,old X,let me look!

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          4 weeks ago, hide # ^ |
           
          Vote: I like it -13 Vote: I do not like it

          不要！

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            4 weeks ago, hide # ^ |
             
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            They spoke English but I think only Chinese people can understand what they were talking about, because it is "Chinglish".

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            4 weeks ago, hide # ^ |
             
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            Even if you use AI to translate it, you still won't know what weird things they are talking about, because China's internet environment has produced some weird things that only Chinese people know.

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              4 weeks ago, hide # ^ |
               
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              I've lived in China my whole life. I still only understand like half of it. Ahem. (And yes a bunch of what they're talking abt is just uh things that are best left in Chinglish, so that most people wouldn't understand...)

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                3 weeks ago, hide # ^ |
                 
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                They call 'JC' stealing one's account and doing bad things with it, especially in things they call "机房惨案", which means 'a bad plot in a computer room'

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            4 weeks ago, hide # ^ |
             
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            In fact, even as a Chinese person, it's not easy for me to fully understand this sentence.

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              4 weeks ago, hide # ^ |
               
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              Dat's 'cuz you're a good student which is not polluted by your "fox friend dog mates" (I'm surely not good @ English, but I can't speak Chinese, or my contribution will never $$$ \gt 0$$$ qwq).

              Well, I don't know what $$$1$$$ means.

              Sometimes it's disgusting to connect sth. with another thing, like Chengdu and something not able to say. Chengdu is a nice city, though I'm not from Chengdu, it surely attracted me when I travelled there. CF (a school located in Chengdu) OIers are welcoming, and Jinjiang river is nice.

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                4 weeks ago, hide # ^ |
                 
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                I'm from Chengdu. Chengdu is a good city.

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                3 weeks ago, hide # ^ |
                 
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                Well, you're quite right. I should say sorry to everyone who saw my comment. It's not only for the reason that I ruins the eyes with my terrible comments, but also my politeness. It's an awful decision to play jokes about Chengdu and gays. Although we always connect them in talk as meme, it's improper to speak in this way on the Internet where competitors all over the world discuss problems. It's my mistake to behave so crazy on the website. I'm sorry. 要不我赔你点钱吧。

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                  3 weeks ago, hide # ^ |
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                  I'm sorry, too. 我也可以赔你点钱。

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                  3 weeks ago, hide # ^ |
                   
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                  If you keep such speaking way, I will f**k you with my big red sausage.

                  这不叫赔钱，这踏马叫嫖唱。

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                  3 weeks ago, hide # ^ |
                   
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                  我喜欢你。

                  I love You.

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4 weeks ago, hide # |
← Rev. 2  
Vote: I like it +48 Vote: I do not like it

My Codeforces rating is 1959, while yql0991666's is 2061.

Although I know that my total score of 313 in the Chinese NOI is low (Ranked in the lower half of the bronze medal tier), I still think I’m much stronger than a contestant who isn’t even eligible to participate in the provincial competitions (CSP-S and NOIP).

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4 weeks ago, hide # |
 
Vote: I like it +11 Vote: I do not like it

It's pretty annoying to see cheaters in contests,especially those who use AI.All they can do is to show off themselves even though they don't have the abililty to do so,and it's even worse that they will spread anxiety to others.

I think this should be stopped.

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4 weeks ago, hide # |
 
Vote: I like it +12 Vote: I do not like it

its actually so disappointing that people do such things, even after cp is so fun

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4 weeks ago, hide # |
 
Vote: I like it +14 Vote: I do not like it

yql0991666 is obviously a cheater. Ban the cheater please.

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Vote: I like it +23 Vote: I do not like it

I can't imagine how a CPer can arrive 1900 rating while he can't got CSP-J first prize.

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← Rev. 2  
Vote: I like it +5 Vote: I do not like it

I have read it with great attention.

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4 weeks ago, hide # |
 
Vote: I like it +11 Vote: I do not like it

why people cheating in cf? You cant earn money or get something with your rating. I though cf its about lesson

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    4 weeks ago, hide # ^ |
     
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    it's for putting a link to your cf account on resumes so that they have a higher chance of getting hired

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https://codeforces.me/blog/entry/155961 Lets check out what Mr. Cheater wants to tell us.

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4 weeks ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

yql0991666 is definitely weaker than me.

Because I got 160 points in NOIP2025 , about 200 points in CSP-S , while yql0991666 only got 130 points in CSP-J.

emm.yes.?!

ma,ybe.!

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4 weeks ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

I notices that the suspect made a 30pts progress in CSP-J through the gap of one year. I couldn't believe that within 0.8 years, he has become a CM and can get 250~300pts in CSP-S, cuz *2000 problems refer to cyan and blue problems in luogu. But if that's true, I ensure that I'd apologize and I'll look forward to this prospective OIER's AK IOI cordially./xyx

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4 weeks ago, hide # |
← Rev. 2  
Vote: I like it +14 Vote: I do not like it

this guy has already got banned in Luogu LMAO he's obviously a cheater,CF should do something with taht

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4 weeks ago, hide # |
 
Vote: I like it +8 Vote: I do not like it

TestsNumT

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4 weeks ago, hide # |
 
Vote: I like it +6 Vote: I do not like it

terrifying speed of progress! He will up to brown(a tag named"cheater" in luogu).

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← Rev. 2  
Vote: I like it +32 Vote: I do not like it

We shall cheat to the end!

we shall fight on the rating by cheating,

we shall change the style of AI's code for cheating

we shall defend our ranking by cheating, whatever the cost may be,

we shall fight on the CSP-J 2024 100pts,

we shall fight on the CSP-J 2025 130pts,

we shall never abandon cheating!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

and even if, which I do not for a moment believe, there are nothing we can do,

then our Qilong Yin comrade, undoutbedly will killed all problem in CSP2026 because he is a strong CM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

by yql0991666

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4 weeks ago, hide # |
 
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yup, his style is enough to say he is cheating

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← Rev. 4  
Vote: I like it -21 Vote: I do not like it

what's the meaning

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4 weeks ago, hide # |
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.

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3 weeks ago, hide # |
 
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Link It's the third problem of CSP-J last year. That means, if you can solve it, you can probably get 300pts in CSP-J.

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3 weeks ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

So, what will cheaters become in Codeforces?

(Idw to check the rule posts now)

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3 weeks ago, hide # |
 
Vote: I like it +27 Vote: I do not like it

MikeMirzayanov Vladosiya

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3 weeks ago, hide # |
 
Vote: I like it +13 Vote: I do not like it

why can he CM? I can get the first prize in CSP-J...

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3 weeks ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

So did anyone still remember SudoXue

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3 weeks ago, hide # |
 
Vote: I like it +8 Vote: I do not like it

At this point , I just do it for fun not for rating .... there is no proper way to identify all cheaters ig :')

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    3 weeks ago, hide # ^ |
     
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    since chatgpt and other LLM become stronger, I gradually lost interest in participating online contest.

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3 weeks ago, hide # |
← Rev. 3  
Vote: I like it +5 Vote: I do not like it

Recent news: yql0991666 gets rank 54 (without unofficial) in Round 1117, having solved F1 while not solved D. This sign make him more suspicious of cheating.

upd: corrected the wrong problem id from "E1" to F1.

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3 weeks ago, hide # |
 
Vote: I like it +12 Vote: I do not like it

yql0991666, could you explain 387437964 387437988 how can you write 1.6KB code in 3 seconds?

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    3 weeks ago, hide # ^ |
     
    Vote: I like it +13 Vote: I do not like it

    Looking at the code for Problem E, what kind of person would write such a long definition on a single line (the fourth line)?

    If you interpret this as a way to make the code more compact (by consolidating lines), then why are the assignment statements on lines 19 through 24 separated?

    The only explanation is that the AI-generated code was partially modified.

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3 weeks ago, hide # |
← Rev. 2  
Vote: I like it +19 Vote: I do not like it

He became Master yesterday... Please ban him codeforces, he'll get LGM soon if we doesn't stop him.

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3 weeks ago, hide # |
 
Vote: I like it +29 Vote: I do not like it

Cheating Master

Yes.

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Look at his most recent performance... he solved problem B in less than a minute! Wow he's so great! I want to be just like him when I grow up! (bushi

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I am amazed that he has cheated again.

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When others increase their ratings, they take the stairs, but yql0991666 takes the elevator—an elevator whose brakes have failed, going straight to the top. However, I believe that the elevator he is riding will eventually reach the apex, crashing forcefully into the top-level support beam and completely destroying the account. It now seems that day is not far off.

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BitByBit123 pls can you make blog about suspicios Master azizs look how he participated at last contest as a proof (he got 5th place in official standings but he's a noname guy)

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3 weeks ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

Hello! I am Yin Qilong from 2030! I will tell you 2 good news!

  1. I, yql0991666, am finally banned in Codeforces!!! And I failed the senior high school entrance exam and cannot attend senior high school!!!
  2. wangzeyu2013 finally AKed IOI 2030!!!!! stO wangzeyu2013 Orz!
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    Yeah that's right.

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    103 minutes ago, hide # ^ |
     
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    sto Cute_Wazzy orz

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There we go.He just became master.Good news huh?

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Vote: I like it +22 Vote: I do not like it

Good News! yql0991666 have been banned!

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Vote: I like it +21 Vote: I do not like it

Congratulations! The cheater has been banned. I hope more cheaters will be found and ban the in future!

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Vote: I like it +16 Vote: I do not like it

Congratulations on banning yql!

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Vote: I like it +19 Vote: I do not like it

Good job banning, Codeforces did the right thing

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Vote: I like it +16 Vote: I do not like it

Justice has been served.

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Vote: I like it +28 Vote: I do not like it

I, yql0991666, am finally banned! Congratulations to me!

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https://codeforces.me/contests/with/Pirate-King (https://codeforces.me/contests/with/Pirate-King)

check this guy his name is rahul singh and he is cheating so smartly that no one can catch him. 6 months back he was an expert and all of sudden he can become international master. I know it is possible but he cant do that with very few problems solved.

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