Educational Codeforces Round 81 [Rated for Div. 2]
Difference between en4 and en5, changed 2,598 character(s)
Hello Codeforces!↵

On [contest_time:1295] [contest:1295] will start.↵

Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.↵
 ↵
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.↵
 ↵
You will be given **6 problems** and **2 hours** to solve them.↵
 ↵
The problems were invented and prepared by Roman [user:Roms,2020-01-13] Glazov, Adilbek [user:adedalic,2020-01-13] Dalabaev, Vladimir [user:Vovuh,2020-01-13] Petrov, Ivan [user:BledDest,2020-01-13] Androsov, Maksim [user:Ne0n25,2020-01-13] Mescheryakov and me. Also huge thanks to Mike [user:MikeMirzayanov,2020-01-13] Mirzayanov for great systems Polygon and Codeforces.↵

Good luck to all the participants!↵

Our friends at Harbour.Space also have a message for you:↵

<center>↵
<img alt="Hello Muscat" src="https://codeforces.com/predownloaded/39/43/39438cb087a7df2453a39ddda09e4dadd9848cf1.png" style="float:center;height: 300px; margin: 10px; max-width:50%;"/>↵
</center>↵

_Hi Codeforces!_ ↵

_As a special prize for the Educational Round 81, we would like to invite the top participants to take part in our [Hello Muscat ICPC Programming Bootcamp](https://icpc.harbour.space/?utm_source=codeforces&utm_medium=partners), which will take place in Oman, from March 19 to March 25, 2020. The prize will cover the participation fee, accommodation, and half-board meals for the entire duration of the bootcamp (except flights)!_ ↵

_**There are three requirements to satisfy:**_ ↵
  ↵
- _You took part in at least 10 rated contests on Codeforces_↵
- _Your max rating should be less than 2400_ ↵
- _You should be eligible for ICPC and/or IOI 2020+_↵

<center style="margin:2.5em;">↵
<a href="https://codeforces.com/userForm/614b4a7f341c05b2" style="text-decoration:none; font-size:20px; background-color:#523996; color:white; font-weight:bold; padding:0.5em 1em;">Fill out the form&rarr;</a>↵
</center>↵

_Good luck to everyone!_ ↵

_We are also excited to announce that we are working with our partners to provide free participation (flights not included) for the teams going to the ICPC World Finals 2020, which will take place in Moscow. If you and your team qualified for the Finals, fill out the form below to see if you’re eligible._ ↵

<center style="margin:2.5em;">↵
<a href="https://docs.google.com/forms/d/e/1FAIpQLSeiEkhucSWbHYqjj792C8bCwH-WvHBDCPL85S8p_6pg22Picw/viewform" style="text-decoration:none; font-size:18px; background-color:#00796B; color:white; font-weight:bold; padding:0.5em 1em;">Apply Now&rarr;</a>↵
</center>


Congratulations to the winners:↵
<table class='bordertable'>↵
<tbody>↵
<tr>↵
<th>Rank</th>↵
<th>Competitor</th>↵
<th>Problems Solved</th>↵
<th>Penalty</th>↵
</tr>↵
<tr>↵
<td>1</td>↵
<td>[user:nickluo, 2020-01-29]</td>↵
<td>6</td>↵
<td>177</td>↵
</tr>↵
<tr>↵
<td>2</td>↵
<td>[user:KrK, 2020-01-29]</td>↵
<td>6</td>↵
<td>184</td>↵
</tr>↵
<tr>↵
<td>3</td>↵
<td>[user:NoLongerRed, 2020-01-29]</td>↵
<td>6</td>↵
<td>185</td>↵
</tr>↵
<tr>↵
<td>4</td>↵
<td>[user:Anadi, 2020-01-29]</td>↵
<td>6</td>↵
<td>200</td>↵
</tr>↵
<tr>↵
<td>5</td>↵
<td>[user:neal, 2020-01-29]</td>↵
<td>6</td>↵
<td>204</td>↵
</tr>↵
</tbody>↵
</table>↵


Congratulations to the best hackers:↵
<table class='bordertable'>↵
<tbody>↵
<tr>↵
<th>Rank</th>↵
<th>Competitor</th>↵
<th>Hack Count</th>↵
</tr>↵
<tr>↵
<td>1</td>↵
<td>[user:GiantTornado, 2020-01-29]</td>↵
<td><b><font color="green">58</font></b></td></td>↵
</tr>↵
<tr>↵
<td>2</td>↵
<td>[user:rachit_raj, 2020-01-29]</td>↵
<td><b><font color="green">51</font></b><b>:<font color="red">-1</font></b></td></td>↵
</tr>↵
<tr>↵
<td>3</td>↵
<td>[user:harshraj22, 2020-01-29]</td>↵
<td><b><font color="green">41</font></b><b>:<font color="red">-5</font></b></td></td>↵
</tr>↵
<tr>↵
<td>4</td>↵
<td>[user:Ahmad__, 2020-01-29]</td>↵
<td><b><font color="green">35</font></b><b>:<font color="red">-1</font></b></td></td>↵
</tr>↵
<tr>↵
<td>5</td>↵
<td>[user:_sad_, 2020-01-29]</td>↵
<td><b><font color="green">33</font></b><b>:<font color="red">-2</font></b></td></td>↵
</tr>↵
</tbody>↵
</table>↵
1096 successful hacks and 873 unsuccessful hacks were made in total!↵

And finally people who were the first to solve each problem:↵
<table class='bordertable'>↵
<tbody>↵
<tr>↵
<th>Problem</th>↵
<th>Competitor</th>↵
<th>Penalty</th>↵
</tr>↵
<tr>↵
<td>A</td>↵
<td>[user:antontrygubO_o, 2020-01-29]</td>↵
<td>0:01</td>↵
</tr>↵
<tr>↵
<td>B</td>↵
<td>[user:neal, 2020-01-29]</td>↵
<td>0:05</td>↵
</tr>↵
<tr>↵
<td>C</td>↵
<td>[user:IgorI, 2020-01-29]</td>↵
<td>0:07</td>↵
</tr>↵
<tr>↵
<td>D</td>↵
<td>[user:NoLongerRed, 2020-01-29]</td>↵
<td>0:06</td>↵
</tr>↵
<tr>↵
<td>E</td>↵
<td>[user:A_Fan_of_the_AK_King--lk, 2020-01-29]</td>↵
<td>0:14</td>↵
</tr>↵
<tr>↵
<td>F</td>↵
<td>[user:Combi, 2020-01-29]</td>↵
<td>0:23</td>↵
</tr>↵
</tbody>↵
</table>↵

**UPD:** [Editorial is out](https://codeforces.com/blog/entry/73467)

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en5 English awoo 2020-01-30 19:41:01 2598
ru4 Russian awoo 2020-01-30 19:40:19 2581
ru3 Russian Una_Shem 2020-01-28 19:14:12 176
en4 English Una_Shem 2020-01-28 19:11:53 4 Tiny change: 'font-size:20px; backgr' -> 'font-size:18px; backgr'
en3 English Una_Shem 2020-01-28 19:10:20 166
ru2 Russian Una_Shem 2020-01-28 18:26:31 1753 (опубликовано)
en2 English Una_Shem 2020-01-28 18:25:26 1672 (published)
en1 English awoo 2020-01-28 10:05:43 1280 Initial revision for English translation (saved to drafts)
ru1 Russian awoo 2020-01-28 10:03:48 1396 Первая редакция (сохранено в черновиках)