Hello everyone,
The Iranian Combinatorics Olympiad is back!
For those who are not familiar with this competition, this is an online event which is free to register and participate in. Everyone can participate in this challenge in a team of at most 3! Keep in mind that all members of a team must have the same nationality!
The contest contains two rounds and students will be challenged to solve IMO style combinatorial questions.
The unique and nice thing about this contest, is that it is the first contest in the world that has an online judging system for a theoretical exam. The registration is now open!
Anyone in any grade and educational level can participate in this exam.
There will be four divisions in this contest:
1) Junior Level: Students in grade 8 or below
2) Intermediate Level: Students in grade 10 or below
3) Advanced Level: Students in grade 12 or below
4) Open Level: No age restrictions
As I mentioned above, this contest is completely free and we are relying on sponsors to support such an event! To help us grow and make this contest is bigger, the only request that we have from you guys is to:
1) Participate in this event if you are interested in solving these types of problems
2) If it is possible for you, we would be happy if you can send us a short video (to our official email), introducing yourself, your nationality and say "OLAMPIAD TARKIBIAT IRAN" which translates to "Iranian Combinatorics Olympiad". We would like to thank you in advance for your kind support.
The event will be on two days, 30th and 31st of October.
official website: https://ico-official.com email: [email protected]
If you have any questions, you can ask under this blog and I will try my best to answer them as much as possible.
Teams qualified for the second day exam in the Advanced level
[Iran] Peyman Sirfi, Sina PourKashani, Pouya Daftarian
[Iran] Arsha Azizeddin, Amir hossein tayyeb, Alireza sharifi
[Iran] Hamid Shafizadeh, Bahamin Shafaghi, Hamed Ghaffari
[Iran] Ahoora Karzanganeh, AmirMahdi SaeidMehr, Iliya Forooghi
[Pakistan] Aayan Faraz Shaikh
[Turkey] Kerem Gelir, Demir Altan Akıncı, Muhammed Selim Çavaş
[Iran] Abolfazl Dalvi, Mohammad EmamJomeh, Yasin Bakhtiar
[Hong Kong] Kwan Yung Ho, Jason Chong Tsz Sing, Sze Long
[Romania] CezarForces, Iancu-Ioan Sandea, Matei Neacșu
[Italy] Andrea, Giuliano, Tommaso
[Malaysia] Ho Janson, Ivan Chan Guan Yu, Yeoh Yi Shuen
[Iran] Kian Noorbakhsh, MohammadHosein NikAmal, AmirHosein Karimi
[Vietnam] Nguyen Dang Duc Tuan, Duong Dinh Phu, Nguyen Phuong Uyen
[Iran] Sam Arvandi, Arash Ostad sharif memar, Kamrad Naghibi
[India] Vihan Vishad Patel, Aarav Anil Rao, Raghav Mukhija
[Iran] Ali Emadi
[Iran] Alireza Jafari, MohammadSadra Allami, Ehsan Mohseni
[Vietnam] Mai Thanh Kien, Trinh Le Hung, Le Minh Duc
[Iran] Ali RabieiFar, Seyed Mohammad MoosaviZadeh Jazayeri, AmirMohammad Namdar
[Malaysia] Boon Qing Hong, Loh Kwong Weng, Vee Hua Zhi
[United Kingdom] Sum Yuet Keisha Kwok, Thomas McCormick
[Spain] Kendry Quiñones Villarreal, Liss Marian Estevez Suárez
[Romania] LucaLucaM, David Mathe, Cristian Gabriel Vergelea
[India] Daksh Aggarwal, Kavya Kumar Taneja, Vedansh Saha
[Bosnia and Herzegovina] Nermin Malićević, Adnan Osmić, Mirza Bušatlić
[China] Xiaolin Zheng, Zhongyi Li
[Bangladesh] Mirza Fayyaduzzaman
[Turkey] Oğuz Fatih Tepe, Semih Yeşilkaya, Poyraz Deniz Koçulu
[Italy] Matteo Cappiello, Anna Kazhamiakina, Barbara Catino
[Georgia] Saba, Cotne, Nika
[Bangladesh] Md Nafis Noor Taseen, Tahsin Khan, Abdullah Al Jarif
[Pakistan] Muhammad Daniyal, Hashir Naimat, Muhammad Mahad Arif
[Indonesia] Steven Abiel Cahyono, Labib Habibillah, Jayden Jurianto
[Georgia] Tsotne Chavchavadze, Zurab Papidze, Ilia Mamiseishvili
[Indonesia] Arsha Naufal Mauritzan, M. Irsyad Asrif, Daffa Atha Arkana
[Belarus] Stephanie Shuturminskaya, Denis Vistunov
[United States] Alexei Potter
[Serbia] Dimitrije Atanasković, Lazar Kolundžija, Lazar Filipović
[Philippines] Kody G. Briones, Iris Lexi Q. Ababon, Matthew Andrei C.H. Go
[Slovakia] Patrik Franek, Martin Franek, Martin Rotter
[Colombia] Gabriel Santiago, Jholger Enriquez, Samuel Pertuz
[France] Anthony Pham, Thibault Monnier, Iyed Saidana
[Algeria] ABOLGHASEMI kian, Chouaib Abderrahim KHEBABZA, SI AHMED Abd Errahmane
[Uzbekistan] Sardor Urazaliev, Ziyovuddin Rakhmonov, Farrukh Bo’ribekov
[Tajikistan] azerila
@icoOfficial
Teams qualified for the second day exam in the Open level
[Iran] sohsoh, ParsaDox, voidXD
[Iran] ArshiaDadras, AliShahali1382, aarr
[Iran] Mohammad Mirzadi, Mohammad Amin Jafari zadeh, Alireza Rezammand
[Australia] Parsa Pordastan, Lucas Chan, Indra Kusumah-Kasim
[Romania] Alexandru Benescu, Luca Metehau, Luca Perju
[Russia] Mikhail Kurs, Ivan Korshunau, Ilia Lobatskii
[Iran] Amoo_Safar, Sam Khanaki, MohammadReza Badri
[Iran] Seyed Rayan Asadi, AliAkbar Mazloom, Bardia KhoshEghbal
[Iran] Sina Azizeddin, AmirMohammad Bandari Masoole, Pouria Mahmoudkhan Shirazi
[Iran] Amirreza Dorosti, Parsa Sadeghi, Radin_Zahedi
[India] Aayush Gajeshwar, Vishesh Kumar Singh, Aarya Bhatt
[Vietnam] Võ Trọng Khải, Nguyễn Bùi Anh Kiệt, Nguyễn Hoàng Phương
[Switzerland] Marco Vaccaro, Mark Neumann, Jerry Schupp
[Iran] Iliya Mohseni, Alireza Rahimi, AmirHosein FarkhondehFar
[Poland] Yaroslav Pryatkin, Pavel Yurashevich, Aleh Sirata
[Bolivia] Mauricio Flores Claros, José Darío Flores Claros, Santiago Ezequiel Flores Claros
[Singapore] errorgorn, Tan Si Jie, yuto1115
[United States] reirugan, Hori, omeganot
[Iran] Sina Torkashvand, Pooya Pakseresht, Mohammadjavad Akbari
[Iran] Ali Moradi Shahmiri, patak, Kalam
[Brazil] Pedro Henrique Ursino, Pedro Borges, João Rafael Silva Azerejo
[Malaysia] Boon Qing Hong, Loh Kwong Weng, Vee Hua Zhi
[Malaysia] Tan Min Heng, Cheng You Seng, Chai Feng Ze
[Bangladesh] Muttakin Ahmed Chowdhury, Tahjib Hossain Khan, Ashraful Islam Fahim
[Georgia] Vano Kakiashvili, Saba Tsirekidze, Giorgi Ambokadze
[Brazil] Vitor de Oliveira da Silva, Rafael Martins Ruas, Leonardo Carvalho de Luca
[Vietnam] Chu Văn Linh, Đinh Thái Sơn, Đỗ Hải Đăng
[Italy] Valentino Zhou, Filippo Gargiulo, Gianluca Baldon
[Belarus] Matsvei Zorka, Denisov Vasily, Manastyrski Maksim
[India] Urjit Paul Chowdhury, Ritwick Pal, Atmadeep Sengupta
[France] Cezara Danciu, Ted Qamo, Omar Cherif
[Nepal] Kritesh Dhakal, Bastav Khatiwada, Aryan Jha
[Sweden] Haire, redkar, Mikael Häglund
[Syria] Mohammad Al Homsi, Mouhammad Ali Hourieh, Saria Ramadan
[Turkey] Emre Osman, Şevket Onur Yılmaz, Hakan Gökdoğan
Auto comment: topic has been updated by aryanv (previous revision, new revision, compare).
Hey!
I tried to register our team and got Server Error 500. And now it's said that emails are already taken :)
Can you please help me figure out this situation?
Team name: Yerevan_SU_2813
Hi can you please send me your emails and grades in a private message? I will ask the technical team to investigate your situation and get back to you.
is it okay if not all team members participate in the first round due to time conflict?
No there is no need that all the team members participate in the first round! Your team must participate in the exam as a whole so there is no problem if one of your team members cannot make it to the first round
thanks for the clarification!
What time is it?
What's the intended difficulty level?
So it is going to be started at 14:00 pm (Iran’s standard time) Which is equivalent to 10:30 am (UTC)
To have a clue about the difficulty of the exam, my suggestion is to take a look at the previous exam’s booklet which is available in the official telegram channel here: https://t.me/ICOofficial
Thanks!
How long will it last for? I want to make sure it fits into my class schedule before registering :)
the first round which is on Thursday is going to be 2 hours long
the second round which is on Friday is going to be 5 hours long (if you are in the Junior or Intermediate level, you don’t need to worry about this round)
Thank you so much for bringing this contest back once again!!
Should we expect similar difficulty level as last year's exam?
Yes, you should roughly expect a similar difficulty level except the Junior level exam which we are introducing for the first time for students in grade 8 or below!
"International medals will be announced after the offline participants-scores have been received from the countries."
Why are the international medals still not announced for ICO 2024?
aryanv please address the issue.
I am trying to address that for you guys :)
The results announced during the final ceremony but we all expect it to be also available on the website as well. I am keep asking the technical team for that and the latest news that I have is that it should be on the website in a few days.
This is the first year that we are introducing official certificates for the international teams which will be emailed to you after the contest by the international team if your team achieves one.
helooo! i have a few questions
1) can i participate on my own?
2) what if my teammate lives and studies in the same country and school with me, but he is a citizen of another country where he no longer lives?
can you answer my questions please?
Hello
sorry and apologies for my delay in responding to your question!
you are very welcome to participate as a team of one as there is not any rules against that!
You can use the nationality that you both study in! That is absolutely fine with us
yes you can participate on your own .
PLEASE BE AWARE THAT THE REGISTRATION WILL BE CLOSED IN 3 DAYS.
REGISTER FOR THE EXAM IF YOU WOULD LIKE TO PARTICIPATE IN THIS EXAM.
so , tell me if i am correct firtsly we will have 1 tour on 30-th october at 10.30 (UTC) and how much will it last? and then if my team wrote exam very good we will have second round on 31-th october yea? and how much that will last can you tell me and what time will it start? and can the time have 2 11-th graders and 1 10-th grader?
yes you right but I'm not sure about the exact time in Iran (its 2 until 3) but in your country I'm not sure sorry .
Its great, looking forward to ICO 2025 aryanv but where will the 1st round be held ik its online but which platform?
It will be held in tbe website of the competition
ico official contest website?
Yes!
Thank you aryanv !
I wish I could participate, but I am not from Iran
You can still participate its an International contest. (does not matter you are from Iran or any other Country)
ohh nice, thanks
Yes he is indeed right! I know that the name is misleading but 65 countries across the world is competing in this nation! That number is more than the number of countries participating in many international olympiads!
Hello, are we allowed to run code during the contest?
Hello, Yes
Is there a comprehensive rulebook on what is and isn't permitted?
Is there any resources like any previous years problems to get out selves familiar with the Olympiad?
Samples are available at the website and the Telegram Channel: https://t.me/ICOofficial
Are the registrations still open ??
You can check the website but I don’t think so!
I think the registration was closed last night!
So is there no other way to register now? me and my friend would really like to participate
You can email the officials but I don't think there is anyway to participate in this year's event any more.
How can i register my team?
The registration was closed last night!
this is really out of my hands and I can’t help you with this.
aryanv Hey! The event isreally knocking at the door (just tomorrow!), and I wanted to clear a couple of small doubts.
Is https://ico-official.com/en/panel/exams this the place where the contest will take place? Will there be an option to submit answers individually for each question, or do we have to compile or take photo of the working & everything together and submit at once?
Just curious what other teams got for the first round. We got
5148
13
30
801
5230697472000
9765624
2841
38
1
2 (but we think its 12)
5051
10
26 (prob wrong)
76
2560
Looks like we match you on nine of them (incidentally we also got 2 on P10), but several of them were guesses / unsure.
By the way, what were your 38 constructions on problem 8? I counted a smaller number but I'm concerned I may have missed some.
From what I understood from the person on my team that solved it, they are:
all combinations of 1s and 2s -> 25
some x-s and one x+1, where x is a divisor of 24 without 1 -> 7
some x-s and one 1, where x is a divisor of 24 without 1, 2 -> 6
This gives 25+7+6=38
Edit: looking at the last revision of the comment
Yes you're right oops. I missed the last case.
The last was some x-s and one 1, I fixed it in the original, my bad.
By the way, do you catch the case of 1 four and 9 fives? I think this also works, but I don't see which case it falls under.
Yup, that doesn't fall in any case, so it would give 39. I asked LucaLucaM (the guy below) if they are sure, and they brute-forced it, so 39 is probably correct.
I see. I put 33 because I got the first two cases as well as the case 1 four and 9 fives (25 + 7 + 1 = 33), but I missed the six solutions in the third case because I erroneously thought that $$$\max - \min \lt 2$$$.
For the ones we are sure about I can confirm the answers (all except 2, 9, 13, 15).
We did not solve 9, but I think I found an example coloring for k=1 (RBRBGBGBGRGRGRB), and since k=0 also works the answer can't be 1. Correct me if I'm wrong. [Edit: after some discussion with another team, they proved the answer is 2, so k={0, 1} are the only ones]
At 10 I am also not sure about the correct interpretation, but since it specifies that the balls are numbered and that info is not used later in the problem, I figure it just means that rotations are considered distinct, which would make the answer 12. It isn't made clear in the statement whether rotations are distinct, so it would be nice if someone can confirm which interpretation is correct.
our p7 solution was wrong for smaller ns (bruteforced) but the answer for n=15 was same as you and some others?? what was your solution then
Here's what our team got
Looks like we match on 1-7, 11, 13, 14. I also believe your answer to 8 is correct; I got it incorrect. (Unfortunately I fakeproved that $$$\max - \min \lt 2$$$, which is not true.)
I hope that you all have enjoyed the contest!
This year is going to be a bit different for the International Teams as I insisted that last year we did not give them enough attention!
Stay tuned for this year...
We will likely have a short interview with the top teams.
Official certificates will be sent as well. (After both rounds are completed)
we got 10/15, 47th on the scoreboard
When will the results of the first round be announced?
In the Telegram channel at most by 10:00 pm Iran’s Standard Time (around 4 hours and 15 minutes from the time I am writing this comment)
Is there a webpage that we can access?, because I don't have Telegram.
I will post the qualified teams here as well
Hello, how will the selected teams be notified? Through the website or email?
Typically through telegram channel, but I will post the results under this post as well!
Thank you :)
ATTENTION: According to the decision of the organizing committee, in the Advanced and Open levels, the procedure for teams to qualify for the second day is as follows:
1) In each level, the top 10 Iranian teams will advance to the second day of the contest.
2) From each country other than Iran, in each level, the top two teams in the first day’s ranking will be considered, and among them, in the Advanced and Open levels, respectively the top 30 and top 20 teams will qualify for the second day.
3) In addition to the two cases above, in each level, the top team from countries that do not yet have any representatives qualified for the second day (based on rules 1 and 2) will be considered, and among them, the top 5 teams will advance to the second day.
Scoreboards are out!!
junior
Intermediate
Advanced & Open
@icoOfficial
Hey what will be the medal cutoff for junior and rough estimation?
How will this year’s international medals be awarded?
At each level, the top 2 teams from each country are placed on the master list (except for the host country, which has 10 teams on the master list). The first one‑twelfth of the teams on the master list will receive gold medals, the next one‑sixth will receive silver medals, and the next one‑third will receive bronze medals.
Note that in the ranking, both the results of the online competition and the results of the offline competition are taken into account.
@icoOfficial
So say a country overperformed, even then, only the first 2 from the country would place?
On the official results page for Advanced it appears that our team (I_Cry_Often) did not answer problems 3 and 6 (if that is what blank means), although we did answer them, afaik correctly. We also have a screenshot from the contest that shows our answers shortly before it ended. What should we do in this situation?
You can email the organizers to see if they can help you on that.
But correct me if I’m wrong, your team is in the Advanced division and second in Romaina (in the division) so I don’t think that either way you have a problem for qualifying for the next round.
Scoreboards got updated
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Qualified teams in the advanced div announced
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Subject: Feedback on 2025 Medal Allocation Criteria
Dear ICO Organizing Committee,
I hope this message finds you well. I’m writing as a participant in this year’s Iranian Combinatorics Olympiad (Intermediate), on behalf of my teammate and myself.
First of all, we deeply appreciate the effort your team puts into organizing such a rigorous and enriching competition. It’s one of the few contests globally that allows students to truly challenge themselves in combinatorics at an international level.
However, we wanted to respectfully raise a concern regarding the new medal allocation rule introduced this year. Specifically, the system where only the top two teams from each country are placed on the master list before global medals are awarded.
We understand the intention might be to ensure geographical representation, but in practice, this system seems to undermine fairness for countries with larger participation pools. For instance, India alone had around 21% of the total contestants, with 72 teams. Is it truly fair to take the best 2 from 72 teams in India, yet take 2 from Bosnia, where in fact only one team even participated and had placed at 78th? (We are not attempting to demean anyone.) That means many teams that ranked well globally, within the top 15–20% overall, were automatically excluded from medal eligibility, while lower-ranked teams from smaller delegations remained in consideration.
This change has, unfortunately, made the outcome less reflective of true performance, especially since the results are already normalized between online and offline participants.
We respectfully request that the committee reconsider applying this rule to the 2025 edition, or at least evaluate results both with and without the master list filter. The current edition’s participants prepared and competed under the understanding that medals were based on overall global rank, as was the case in previous years.
We understand future editions may choose a different structure, but we believe applying this change retroactively to this year’s competition creates unintentional inequity. Once again, this competition was amazing, the quality of the problems was superb, and it is truly one of a kind.
Thank you for taking the time to consider this. We deeply value what the ICO represents and hope this feedback helps strengthen its fairness and international credibility in the final results.
Warm regards, On behalf of all participants of the ICO
I think it is more fair than the current system
well what makes you think 139th and 265th placed Georgian teams are more eligible than the 7th, 13th, 14th, 23rd, 27th, 28th, 35th, 41st, 51st, 53rd and 57th placed Indian teams? At the minimum, they should have fixed say top 15-20% from each country to go to the master list.
There is still time for them to make the required decisions. I hope that a better decision is finalized.
i think you understood what he said incorrectly
apologies to @yashadityapaul on my behalf lmao
Well i just meant that it would be better to give medal according merit and a cutoff mark rather than Quota for contries (top 2 teams)
oops completely agree. cutoff rank or cutoff percentage should be the way.
True as a team but doing solo ranking in top 60 Globally still missing bronze due to that country rule hurts
Please convey the info to others who may be affected who can also raise their concerns.
The competition itself was pretty well organized, quality of questions, release of scoreboard in just hours, was special!!
I'm sure the committee will recognize this issue and will take the most suitable decision.
Hope so they make a fair decision
Na i don't support the top 2 team rule. In the previous comment i just wanted to say that this rule is not fair
yes the 2 team rule is not fair, i think they should just take international results from the main list, not from the master list. Maybe they can give different awards for both if they're really insistent on the master list thing but coming like top 60 internationally and losing a medal to some much lower ranked teams just hurts
I understand the idea behind the top-2-per-country rule — promoting global representation is good. But ICO is mainly a talent-based contest, and medals should reflect performance: you do well, you win. When some lower-ranked teams get medals just for being the only ones from their country, it feels more like a quota than merit. I hope the committee finds a fairer balance for everyone.
Curious, but for Round 2 answers, would LaTeX PDFs be acceptable?
most fair international medal criteria ever (sarcastically)
Completely Agreee 100%