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I have to add the contest to gyms soon.

Will the test data be public ? Or maybe add the contest to gym like last year ?

There is one trick to search all cycles of length 3.


It seems that this code is slow but it works in O(n*sqrt) where n is number of vertexes in our graph (i don't remember proof of that). so use compression for numbers to make n = 400'000 not 1'000'000 in worth case

so as you see this part solves when sides look like (x,y)(x,y) (x,z)(x,z) (y,z)(y,z). other cases, when answer looks like (x,x)(x,x)(x,x)(x,x)(x,x)(x,x) or (x,y)(x,y)(x,y)(x,y) (x,x)(x,x) can be solved in O(n*log) with map

D can be solved in O(1) by case-studying.

During contest, I coded a brute-force method to check all the possible assignment of knights and knaves for k ≤ 10. And, find out the pattern for each pair of

How to solve E in ?

Created or updated the text

It is already posted here.

I used combinatorics but failed on test 20. I think I made mistake with counting same numbers.

And tests :)

Will you post the editorial?

How to solve C?

There must not be such situation.

Please send what you think is incorrect using "Feedback" form at the bottom of page.

It looks like you rejudged my solution, and I got extra penalty because of it?

Created or updated the text

Sorry for the delays, the queues are almost real-time now, we thank you for your patience. We will make sure this doesn't happen during qualification rounds.

yep :( we got 2500+ participants instead of usual 1200. Trying to find additional capacity now

Well this is not the best start so far, seems system is already lagging tremendously in the judging :(

I mailed you, but I didn't receive any response.

Sure :)

can Indians participate in this competition???

Could you please work on getting the task archive translated in English? I can see English statements for the tasks from RCC 2016 only... Thanks!

Thank you, we will fix it in the next release

Obviously, no.

No, they have their own system. It's a good idea to take a part in Warm Up round to get used to the system.

Contest will held in Codeforces?

It is necessary to take part in the warm up round in order to take part in qualification rounds?

Just some minor feedback:
for section "How are the solutions checked?", the image is still in Russian (even for English page), so maybe can be considered to be translated. Looking forward to the contest! :)

Thanks, I'll do it. I wasn't sure what is the status of sending prizes.

Hello. Please, mail us to

Last year I was in top 50 and won a t-shirt and a gift. I didn't receive any of those. Did anyone receive their?