PC2021: Intermediate results, Problem 4, week 1

Intermediate results for Problem 3 will be available 17:00 GMT, 4/4/21.

By 28th March 2021, there are 1012 registered participants from 71 countries (the list of countries is given below). During the first week, 12 solutions were submitted, out of which 7 had at least one correct part, a or b, see the 0-th hint.

Correct solutions for the part a were submitted by:

First NameSurnameCountrySchool/Universitydatetime
HuiyuanWangChinaUniversity of Cambridge28/03/202121:28
ZheningLiCanadaSir John A. Macdonald Secondary School29/03/202104:23
LotusChenChinaNo.2 High School Shijiazhuang30/03/202115:56
AntoniaGhitaRomaniaInternational Computer High School of Bucharest01/04/202114:29
OliwierUrbańskiPolandLiceum Ogólnokształcące nr 7 w Poznaniu03/04/202111:52
JoshuaTeoSingaporeNUS High School04/04/202112:27

Correct solutions for the part b were submitted by:

First NameSurnameCountrySchool/Universitydatetime
ZheningLiCanadaSir John A. Macdonald Secondary School29/03/202104:23
NikitaSemeninRussiaMoscow Institute of Physics and Technology29/03/202109:07
OliwierUrbańskiPolandLiceum Ogólnokształcące nr 7 w Poznaniu29/03/202112:18
TevžLotričSloveniaUniversity of Oxford29/03/202122:28

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.