Educational Codeforces Round 73 [Rated for Div. 2]
Difference between en3 and en4, changed 2,745 character(s)
Hello Codeforces!↵

On [contest_time:1221] [contest:1221] 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.me/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 or 7 problems** and **2 hours** to solve them.↵
 ↵
The problems were invented and prepared by Roman [user:Roms,2019-09-18] Glazov, Adilbek [user:adedalic,2019-09-18] Dalabaev, Vladimir [user:Vovuh,2019-09-18] Petrov, Ivan [user:BledDest,2019-09-18] Androsov, Maksim [user:Ne0n25,2019-09-18] Mescheryakov and me. Also huge thanks to Mike [user:MikeMirzayanov,2019-09-18] Mirzayanov for great systems Polygon and Codeforces.↵

Good luck to all the participants!↵

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

![ ](/predownloaded/7f/05/7f052fead14197d0344931c3a1a16af6378f8d5d.png)↵

_Hello Codeforces,_ ↵

_**We want to know what you think about Harbour.Space’s involvement in the Codeforces community**, and how you believe we can improve._ ↵
 ↵
_So we created this short, **5 question survey** to hear your thoughts about how we can provide you with more stuff that you’re interested in, so that we can improve your experience on Codeforces._↵

_**We really value your feedback**, so it would mean a lot if you could take a minute and fill out the survey. Thanks in advance!_↵

<center style="margin:2.5em;">↵
<a href="https://harbourspace.typeform.com/to/jaJ7jR" style="text-decoration:none; font-size:18px; background-color:#523996; color:white; font-weight:bold; padding:0.5em 1em;">GO TO SURVEY&rarr;</a>↵
</center> ↵

**UPD:** [Post about the issue](https://codeforces.me/blog/entry/69897Congratulations 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:kefaa2, 2019-09-19]</td>↵
<td>7</td>↵
<td>192</td>↵
</tr>↵
<tr>↵
<td>2</td>↵
<td>[user:jiangly, 2019-09-19]</td>↵
<td>6</td>↵
<td>152</td>↵
</tr>↵
<tr>↵
<td>3</td>↵
<td>[user:betrue12, 2019-09-19]</td>↵
<td>6</td>↵
<td>187</td>↵
</tr>↵
<tr>↵
<td>4</td>↵
<td>[user:I_love_Tanya_Romanova, 2019-09-19]</td>↵
<td>6</td>↵
<td>196</td>↵
</tr>↵
<tr>↵
<td>5</td>↵
<td>[user:pekempey, 2019-09-19]</td>↵
<td>6</td>↵
<td>198</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:achi_basadzishvili, 2019-09-19]</td>↵
<td><b><font color="green">129</font></b><b>:<font color="red">-46</font></b></td></td>↵
</tr>↵
<tr>↵
<td>2</td>↵
<td>[user:apoorv024, 2019-09-19]</td>↵
<td><b><font color="green">87</font></b><b>:<font color="red">-4</font></b></td></td>↵
</tr>↵
<tr>↵
<td>3</td>↵
<td>[user:Kolo_Ray7, 2019-09-19]</td>↵
<td><b><font color="green">73</font></b><b>:<font color="red">-31</font></b></td></td>↵
</tr>↵
<tr>↵
<td>4</td>↵
<td>[user:lollihunter, 2019-09-19]</td>↵
<td><b><font color="green">52</font></b><b>:<font color="red">-7</font></b></td></td>↵
</tr>↵
<tr>↵
<td>5</td>↵
<td>[user:badmofo21, 2019-09-19]</td>↵
<td><b><font color="green">15</font></b><b>:<font color="red">-1</font></b></td></td>↵
</tr>↵
</tbody>↵
</table>↵
544 successful hacks and 568 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:Chereshnya_, 2019-09-19]</td>↵
<td>0:01</td>↵
</tr>↵
<tr>↵
<td>B</td>↵
<td>[user:Chereshnya_, 2019-09-19]</td>↵
<td>0:02</td>↵
</tr>↵
<tr>↵
<td>C</td>↵
<td>[user:YahiaAshraf74, 2019-09-19]</td>↵
<td>0:04</td>↵
</tr>↵
<tr>↵
<td>D</td>↵
<td>[user:sysjuruo, 2019-09-19]</td>↵
<td>0:08</td>↵
</tr>↵
<tr>↵
<td>E</td>↵
<td>[user:kefaa2, 2019-09-19]</td>↵
<td>0:31</td>↵
</tr>↵
<tr>↵
<td>F</td>↵
<td>[user:Benq, 2019-09-19]</td>↵
<td>0:35</td>↵
</tr>↵
<tr>↵
<td>G</td>↵
<td>[user:Benq, 2019-09-19]</td>↵
<td>1:02</td>↵
</tr>↵
</tbody>↵
</table>↵

**UPD:** [Post about the issue](https://codeforces.me/blog/entry/69897)↵

**UPD2:** [Editorial is out](https://codeforces.me/blog/entry/69925
)

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en4 English awoo 2019-09-20 17:27:42 2745
ru6 Russian awoo 2019-09-20 17:26:52 2723
ru5 Russian awoo 2019-09-19 23:45:48 5 Мелкая правка: 'log/entry/edit/69897)' -> 'log/entry/69897)'
ru4 Russian awoo 2019-09-19 21:34:13 76
en3 English awoo 2019-09-19 21:26:12 74
ru3 Russian Una_Shem 2019-09-18 22:28:22 919
ru2 Russian Una_Shem 2019-09-18 22:09:33 0 (опубликовано)
en2 English Una_Shem 2019-09-18 21:44:28 884 (published)
en1 English awoo 2019-09-18 12:58:16 1285 Initial revision for English translation (saved to drafts)
ru1 Russian awoo 2019-09-18 12:57:35 1403 Первая редакция (сохранено в черновиках)