Hello Codeforces!

I am glad to invite you to my first official round Codeforces Round 630 (Div. 2), which will take place on Mar/31/2020 16:35 (Moscow time) (please note for the unusual starting time) and will be rated for all Division 2 participants.

You will be given 7 tasks and 150 minutes to solve them.

All tasks in this round were prepared by me. Hope that you will enjoy those tasks!

I would like to thank:

• awoo for great coordination of this round, and the idea of solution of one task!

• Nanako, Nezzar for useful discussion and testing this round!

• antontrygubO_o, McDic, vovuh, TBeumsJryi, socho, Oak_limy, Amori, Stresshoover, I1I1I11I1I1, defolaut, hx073269 and Pavlova for testing this round and invaluable suggestions!

• MikeMirzayanov for great systems Codeforces and Polygon!

To avoid queueforces, we will provide small amount but strong (hope so) pretests for first few tasks. Hope it works!

Score distribution will be announced later.

Good luck and have fun!

UPD1: Score distribution: 500-1000-1250-1250-1750-2250-3000

UPD2: Contest is over, and here is the editorial.

UPD3:

I am sorry that pretests were not as strong as I excepted.

Congratulations to the winners:

div1+div2:

1. vepifanov

2. int128.

3. PinkRabbitAFO

4. 300iq

5. nuip

div 2:

1. int128.

2. sorry_to_tourist

3. camilla

4. jerome_wei

5. [user: _dawn]

people who were first to solve each task:

A: white_paperdog

B: MagentaCobra

C: okwedook

D: white_paperdog

E: GsjzTle

F: yooooooooo

G: GoGooLi

Lastly, thanks to Handsome2004 for the brilliant hack of E.