Educational Codeforces Round 90 [Rated for Div. 2]
Difference between en4 and en5, changed 2,620 character(s)
Hello Codeforces!↵

On [contest_time:1373] [contest:1373] 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://mirror.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 or 7 problems** and **2 hours** to solve them.↵
 ↵
The problems were invented and prepared by Roman [user:Roms,2020-06-24] Glazov, Adilbek [user:adedalic,2020-06-24] Dalabaev, Vladimir [user:vovuh,2020-06-24] Petrov, Ivan [user:BledDest,2020-06-24] Androsov, Maksim [user:Ne0n25,2020-06-24] Mescheryakov and me. Also huge thanks to Mike [user:MikeMirzayanov,2020-06-24] Mirzayanov for great systems Polygon and Codeforces.↵

Good luck to all the participants!↵

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:Geothermal, 2020-06-25]</td>↵
<td>7</td>↵
<td>130</td>↵
</tr>↵
<tr>↵
<td>2</td>↵
<td>[user:ksun48, 2020-06-25]</td>↵
<td>7</td>↵
<td>143</td>↵
</tr>↵
<tr>↵
<td>3</td>↵
<td>[user:300iq, 2020-06-25]</td>↵
<td>7</td>↵
<td>147</td>↵
</tr>↵
<tr>↵
<td>4</td>↵
<td>[user:vepifanov, 2020-06-25]</td>↵
<td>7</td>↵
<td>168</td>↵
</tr>↵
<tr>↵
<td>5</td>↵
<td>[user:Radewoosh, 2020-06-25]</td>↵
<td>7</td>↵
<td>175</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:EduPeres, 2020-06-25]</td>↵
<td><b><font color="green">40</font></b></td></td>↵
</tr>↵
<tr>↵
<td>2</td>↵
<td>[user:Grey_Matter, 2020-06-25]</td>↵
<td><b><font color="green">39</font></b><b>:<font color="red">-3</font></b></td></td>↵
</tr>↵
<tr>↵
<td>3</td>↵
<td>[user:lx430621, 2020-06-25]</td>↵
<td><b><font color="green">26</font></b><b>:<font color="red">-1</font></b></td></td>↵
</tr>↵
<tr>↵
<td>4</td>↵
<td>[user:killa_vanilla, 2020-06-25]</td>↵
<td><b><font color="green">25</font></b><b>:<font color="red">-5</font></b></td></td>↵
</tr>↵
<tr>↵
<td>5</td>↵
<td>[user:checkingagain, 2020-06-25]</td>↵
<td><b><font color="green">17</font></b><b>:<font color="red">-1</font></b></td></td>↵
</tr>↵
</tbody>↵
</table>↵
351 successful hacks and 375 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:Geothermal, 2020-06-25]</td>↵
<td>0:01</td>↵
</tr>↵
<tr>↵
<td>B</td>↵
<td>[user:ksun48, 2020-06-25]</td>↵
<td>0:01</td>↵
</tr>↵
<tr>↵
<td>C</td>↵
<td>[user:ksun48, 2020-06-25]</td>↵
<td>0:03</td>↵
</tr>↵
<tr>↵
<td>D</td>↵
<td>[user:Noureldin, 2020-06-25]</td>↵
<td>0:09</td>↵
</tr>↵
<tr>↵
<td>E</td>↵
<td>[user:Geothermal, 2020-06-25]</td>↵
<td>0:22</td>↵
</tr>↵
<tr>↵
<td>F</td>↵
<td>[user:ElOrdyh, 2020-06-25]</td>↵
<td>0:15</td>↵
</tr>↵
<tr>↵
<td>G</td>↵
<td>[user:dario2994, 2020-06-25]</td>↵
<td>0:29</td>↵
</tr>↵
</tbody>↵
</table>↵

**UPD:** [Editorial is out](https://mirror.codeforces.com/blog/entry/79376)

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en5 English awoo 2020-06-28 10:50:07 2620
ru4 Russian awoo 2020-06-28 10:49:47 2596
en4 English awoo 2020-06-26 18:34:59 72
ru3 Russian awoo 2020-06-26 18:34:40 74
ru2 Russian Una_Shem 2020-06-24 19:38:58 0 (опубликовано)
en3 English Una_Shem 2020-06-24 19:38:46 0 (published)
en2 English awoo 2020-06-24 16:46:42 22
en1 English awoo 2020-06-24 16:45:13 1291 Initial revision for English translation (saved to drafts)
ru1 Russian awoo 2020-06-24 16:44:37 1401 Первая редакция (сохранено в черновиках)