Codeforcesβ Sponsored by Telegram (abbr. CF) is a Russian website dedicated to competitive programming. It was created and is maintained by a group of competitive programmers from Saratov State University led by Mikhail Mirzayanov. Every year, CF hosts a lot of competitions like Intel Code Challenge, Russian Code Cup, Codeforces Rounds, etc. It is world-famous because of its challenging problems. A large of Chinese students and hackers also like to solve problems on CF. What's more, the rank system of the competitors is very unique. There are "Red Names"(Legendary Grandmaster /International Grandmaster/Grandmaster)(Legendary Grandmaster has black initial), "Yellow Names"(Master), "Violet Names"(Candidate Master), "Blue Names"(Expert), "Cyan Names"(Specialist), "Green Names"(Pupil) and "Grey Names"(Newbie) according to their rating bounds.

Problem Set

Codeforces Round #353 (Div. 2)

CF 675A CF 675B

Codeforces Round #356 (Div. 1)

CF 679B

Codeforces Round #375 (Div. 2)

CF 723A CF 723B CF 723C CF 723D

Codeforces Round #433 (Div. 1)

CF 853A

Codeforces Round #469 (Div. 2)

CF 950A CF 950B CF 950C CF 950D

Educational Codeforces Round 40 (Rated for Div. 2)

CF 954D