PC2021: Intermediate results, Problem 4, week 7

By 16th May 2021, there are 1050 registered participants from 71 countries (the list of countries is given below). During the first seven weeks, 40 solutions were submitted, out of which 19 had at least one correct part, a or b, see the 0-th hint.

Correct solutions for the part a were submitted by:

First Name	Surname	Country	School/University	date	time
Huiyuan	Wang	China	University of Cambridge	28/03/2021	21:28
Zhening	Li	Canada	Sir John A. Macdonald Secondary School	29/03/2021	04:23
Lotus	Chen	China	No.2 High School Shijiazhuang	30/03/2021	15:56
Antonia	Ghita	Romania	International Computer High School of Bucharest	01/04/2021	14:29
Oliwier	Urbański	Poland	Liceum Ogólnokształcące nr 7 w Poznaniu	03/04/2021	11:52
Joshua	Teo	Singapore	NUS High School	04/04/2021	12:27
Nikita	Semenin	Russia	Moscow Institute of Physics and Technology	05/04/2021	15:55
M. Subhi	Abo Rdan	Syria	Knowledge private schools	08/04/2021	08:56
Caio Augusto	Siqueira da Silva	Brazil	Colégio Objetivo Integrado	13/04/2021	02:16
Vlad-Ștefan	Oros	Romania	“Grigore Moisil” Informatics High School	13/04/2021	16:00
Qian	Lin	China	University of Oxford	01/05/2021	14:47
Yanjun	Zhou	United Kingdom	University of Oxford	02/05/2021	23:29
Ameya Vikrama	Singh	India	FIITJEE Junior College	03/05/2021	10:58
Daniel	Schiller	Germany	Ruprecht-Karls-Universität Heidelberg	08/05/2021	21:44
Vuk	Hip	Serbia	Mathematical grammar school	11/05/2021	08:56
Sebastián Andrés	Arévalo Aguirre	El Salvador	Instituto Emiliani	16/05/2021	06:38
Alexandar	Roussev	Bulgaria	First Language School	16/05/2021	11:21

Correct solutions for the part b were submitted by:

First Name	Surname	Country	School/University	date	time
Zhening	Li	Canada	Sir John A. Macdonald Secondary School	29/03/2021	04:23
Nikita	Semenin	Russia	Moscow Institute of Physics and Technology	29/03/2021	09:07
Oliwier	Urbański	Poland	Liceum Ogólnokształcące nr 7 w Poznaniu	29/03/2021	12:18
Tevž	Lotrič	Slovenia	University of Oxford	29/03/2021	22:28
Huiyuan	Wang	China	University of Cambridge	05/04/2021	00:23
Vlad-Ștefan	Oros	Romania	“Grigore Moisil” Informatics High School	13/04/2021	16:00
Jaroslav	Herman	Czechia	Charles University	28/04/2021	22:04
Yanjun	Zhou	United Kingdom	University of Oxford	02/05/2021	23:29
Qian	Lin	China	University of Oxford	08/05/2021	16:02

Participating countries: Algeria, Azerbaijan, Australia, Bangladesh, Belarus, Belgium, Bosnia and Herzegovina, Bolivia, Brazil, Bulgaria, Cambodia, Canada, China, Croatia, Czechia, Egypt, El Salvador, Estonia, Finland, Georgia, Germany, Greece, Hungary, India, Indonesia, Iran, Israel, Italy, Japan, Kazakhstan, Kenya, Korea, Kyrgyzstan, Latvia, Lebanon, Lithuania, Macedonia, Malaysia, Mexico, Moldova, Mongolia, Nepal, Nigeria, North Macedonia, Pakistan, Peru, Philippines, Poland, Romania, Russia, Saudi Arabia, Serbia, Singapore, Slovakia, Slovenia, South Africa, South Korea, Spain, Sri Lanka, Sweden, Switzerland, Syria, Taiwan, Thailand, Turkey, Turkmenistan, United Arab Emirates, United Kingdom, United States, Uzbekistan, Vietnam.