Today was held the first round of the International Olympiad in Informatics. The first problem was solved by all the participant with Russia (Mikhail Ipatov). On behalf of all the participants (codeforces) to congratulate him srl result on the first day of the Olympics. And as we congratulate two other members who also passed the first day of the Olympic Games with the result of these participants srl (Yuhao Du -China) and participant with Korea (Jeehak Yoon). I propose to discuss the problem here.