내가 돌아왔다! (Hello, Codeforces!)

I am thrilled to introduce you to Codeforces Round #633. Followings are basic information:

• This contest will take place on Apr/12/2020 17:05 (Moscow time).
• The round is rated for all participants who can understand this announcement. There will be two divisions.
• There are 5 problems in each division and you will have 2 hours to solve it.
• Score distribution will be announced later.

Followings are contributors:

• Authors: McDic (All Div.2 problems and Div.1 D), tzuyu_chou (Div.1 E)
• Coordinator: antontrygubO_o
• Testers:
  • Phase 1 (When this round was supposed to be Div.2): dorijanlendvaj, SoulTch, pajenegod, AryaPawn, Rahul, mcdx9524, 300iq, Nemo, tfg
  • Phase 2 (Before we knew that old Div1D can be easily googled): Um_nik, Ari, benson1029, khulegu, Sad_reacts_only, TselmegKh
  • Phase 3 (Before few days to the round): mohammedehab2002, Kuroni, xuanquang1999, JettyOller, enoone
• CF Admins: Thanks to MikeMirzayanov and his team for maintaining Codeforces and Polygon. I would like to say same sentence again as I said in my last round's announcement. Polygon is super great platform to prepare sports programming contest.

Followings are some fun things:

• antontrygubO_o is the most intense coordinator I have ever met. He rejected lots of my problems. Some example of rejection comments are below:
  • This problem is too standard.
  • Don't ask people about theorem and formula.
  • This problem is appeared in recent ptz camp with higher constraints.
  • I don't like it.
  • Rock Scissor Paper makes statement messy, because some people don't know about it.
  • D2A should be easier than this one.
  • I've found generalized version of this problem in POI.
  • Isn't this obvious?
  • Your proof is wrong.
  • This problem is not very interesting.
  • This is too (censored).
• After lots of rejections, I tried my best to make problems to be interesting. I hope you like at least some of my problems.
• This round was originally supposed to be rated for Div.2 only. However, after we completed Phase 1 testing, we found that my round is too hard for Div.2, so we added more problems and made this round to be Div.1.
• In this round, statements will be even shorter than last contest.
• Even for some of problems which my coordinator approved, there were critical issues that made problems to be excluded. I will introduce some of my rejected problems which won't be used anymore in another post, after this contest ends.

I hope everyone can enjoy my third contest. Thanks in advance!

Followings are updates:

1. Score Distribution:
   • Div.1: 500 1000 1500 2000 2750
   • Div.2: 500 750 1250 1750 2250
2. I am sorry for such Div2C/Div1A statement issue. We fixed that immediately after few minutes to the round, but we should have announced it.
3. Editorial is posted: https://mirror.codeforces.com/blog/entry/75913
4. I opened new mashup for excluded problems. These problems are originally approved by antontrygubO_o but excluded for some reasons.
   1. Binomial Determinant is old Div1D. We found this problem on google so we removed this.
   2. Divisible Xor is old Div1A. But since we made 3 xor problems, we removed this one.

Followings are winners:

<Div.1>

1. tourist
2. Radewoosh
3. TLEwpdus
4. ecnerwala
5. gisp_zjz
6. Maksim1744
7. scott_wu
8. Petr
9. jiangly
10. maroonrk

<Div.2>

1. Nachia
2. MyAngelBakapiano
3. 0.142857
4. kekekeke228
5. LeierKing
6. Ka_ng_Hyeon
7. Anithas_love_for_tries
8. confeito
9. TOPCYBERFLOWER
10. wattaihei