**Hello, Codeforces!** ＼(≧▽≦)／

I, Ilya_Is2022, am glad to invite each of you to our interesting SRound #1 (Based on the failed city school championship), which will be held in [contest_time: 447021]! This round was developed independently of the division system created on **Codeforces**, so each participant of the competition will have something to solve (◕‿◕).

The round will be held according to the standard rules **ICPC**! Thus, the **penalty** for each incorrect parcel before the parcel becomes a **complete solution** will **be equal to 20 minutes**.

You will be asked $$$\log_{2} 32\le x\le\log_{2} 1024$$$, where $$$x$$$ is the number of tasks ʕ ᵔᴥᵔ ʔ and **2 hours 15 minutes** to solve them.One of the tasks is interactive. Don't forget to read the instructions for interactive tasks.

The organizers of this round:

**Isaev**Ilya_Is2022**Ilya**is the author of the tasks and the coordinator of the round.**Nekrasov**nekstas**Stanislav**and**Moskaleva**vika1310**Victoria**— authors of tasks.

Words of gratitude:

MikeMirzayanov — for the wonderful platforms

**Codeforces**and**Polygon**.Nikonova Daria—

**for the excellent translation of the terms into English!**Alexfil — for the blue testing of the competition!

metlik — for the turquoise testing round!

donovilia2007, J3RRyE, Risan99, I_R7S_I — for the gray testing round!

#### Go to the context page: SRound #1

**UPD 1:**

The date and time of the event remain unchanged. (As you may have noticed, our round does not overlap with any of the official competitions)

Self-registration for the contest is already

**available**! (Click).See you at the contest

**(｡• ᵕ •｡`)**!

**UPD 2:**

We apologize for the error in the text translation of the English version of tasks D1 and D2.

Thank you all for participating in the round!

**EDITORIAL**: Click

Top of today's participants:

The wizard for solving the wrong D2: Believer.

**The phase of completing and viewing tests with parcels is open!**

excited!!! added to calendar:)

We really hope that no official competitions will be scheduled on this date and time :)

I am so new to codeforces that i today only realized that you can create unofficial contests :O

Excited!!!

Excited for this

How to Solve D2 and Last problem.

For the last problem, I ran a bruteforce on my computer to find all the numbers in the interval (loop over the 1e9 candidate squares, then check if it is a palindrome). This takes a couple minutes to run, but then you get only 21 of these numbers, so you can just paste them in the source code, and for queries just check which of these lie in the interval.

Editorial: https://codeforces.com/blog/entry/117117

I did D2 on the basis of — Number of places I have for the odd and even indices if sum of even or odd ind. cannot fit into it print "NO" else "YES"

I think that the Testcases of D2 might be wrong. Consider the 9th test in Test Case 3. It says that the answer for 0 1 1 should be YES, but I think it should be NO. Can someone please construct a n (without leading zeroes according to statement) which shows why answer for 0 1 1 should be YES?

Yes, seems like.

a,b >= 1 and k >= 0 Could be more clear and easy to think.

Yes, I understand you! the test set is incorrect. The author of the idea of this problem has already been punished for misleading the participants who tried to solve it. In the near future, according to the decision of the authors, this problem will be removed.