Greetings, CodeForces users. CodeForces Beta Round #15 will be held today, 29th of May at 19:00 MSK. My name is Roman Iedmeksyi and I am lucky to introduce this problem set.

I would like to thank Dmitry Matov, Julia Satushina and Mike Mirzayanov for well-coordinated work on this match. Also I would like to mention the contribution of Yaroslav Tverdokhlib in problems testing.

Some information about me:       

I am a student of Kyiv National Taras Shevchenko University. I started programming at school. As my first achievement I had taken third place in Ukrainian Olympiad in Informatics. Next year I’ve worked harder and was qualified to IOI 2009 selection. Unfortunately I had not enough experience to pass.

In this contest I wish you good luck and high results.

UPD contest extended by 15 minutes

UPD Codeforces team apologizes that during today's round the server was regularly unavailable due to different technical reasons. We will try to do our best to avoid similar situations on the upcoming contests. Our apologies for some mistakes in the statements. Because of these reasons today's competition results will not affect your rating.

Looking forward to seeing you at Codeforces Beta Round 16.