Hello! To be absolutely sure that the system technically works well, we moved the upcoming Div1/Div2 round, but on the same day (May, 9) we put the first experimental Div4 round! All details on the link: https://codeforces.com/blog/entry/77028

— MikeMirzayanov

🔥New! Codeforces Round 640 (Div. 4) starts in ~4 hours. Please, join by the link https://codeforces.com/contests/1352

Codeforces Round #641 (Div. 1, Div. 2) starts in ~3 hours. Please, join by this link https://codeforces.com/contests/1349,1350

Codeforces Round 642 (Div. 3) starts in ~4 hours. Please, join by the link https://codeforces.com/contests/1353

Codeforces Round 643 (Div. 2) starts in ~4 hours. Please, join by the link https://codeforces.com/contests/1355

Educational Codeforces Round 87 (rated for Div.2) starts in ~4 hours. Please, join by the link https://codeforces.com/contests/1354

Codeforces Round 644 (Div. 3) starts on 24th of May at 13:35 UTC.
Please, join by the link https://codeforces.com/contests/1360?locale=en

Codeforces Round 644 (Div. 3) starts in ~2 hours. Please, join by the link https://codeforces.com/contests/1360?locale=en

Codeforces Round 645 (Div. 2) starts on 26th of May at 14:35 UTC.
Please, join by the link https://codeforces.com/contests/1358

Codeforces Round 645 (Div. 2) starts in ~2 hours. Please, join by the link https://codeforces.com/contests/1358

Educational Codeforces Round 88 (rated for Div.2) starts on 28th of May at 14:35 UTC. Please, join by the link https://codeforces.com/contests/1359

Educational Codeforces Round 88 (rated for Div.2) starts in ~2 hours. Please, join by the link https://codeforces.com/contests/1359

💥Kotlin Heroes: Episode 4💥 starts on 29th of May at 14:35 UTC.

The round is unrated.

- Top three winners will get prizes of $512, $256 and $128 respectively;

- Top 50 will win a Kotlin Heroes t-shirt and an exclusive Kotlin sticker;

- Competitors solving at least one problem will enter into a draw for one of 50 Kotlin Heroes t-shirts.

We will be glad to see you among the participants!

Please, join by the link https://codeforces.com/contests/1346

🔥Kotlin Heroes: Episode 4 🔥(unrated, 100 t-shirts + cash prizes) starts in ~2 hours.

Please, join by the link
https://codeforces.com/contests/1346

Codeforces Round 646 (Div. 2) starts on 31st of May at 14:35 UTC.
Please, join by the link https://codeforces.com/contests/1363

Codeforces Round 646 (Div. 2) starts in ~2 hours. Please, join by the link https://codeforces.com/contests/1363

Codeforces Round #647 (Div. 1, Div. 2) - Thanks, Algo Muse! starts on 4th of June at 14:35 UTC.
Please, join by the link https://codeforces.com/contests/1361,1362

Codeforces Round #647 (Div. 1, Div. 2) - Thanks, Algo Muse! starts in ~2 hours. Please, join by this link https://codeforces.com/contests/1361,1362

Codeforces Round #648 (Div. 2) starts on 7th of June at 14:35 UTC.
Please, join by the link https://codeforces.com/contests/1365

Codeforces Round #648 (Div. 2) starts in ~2 hours. Please, join by the link https://codeforces.com/contests/1365