Hello, Codeforces!

Educational Codeforces Round 6 will take place on 21 January 2016 at 18:00 MSK for the first and second divisions. You can read about educational rounds here and here.

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The round will be unrated for all users and it will be held with extented ACM ICPC rules. You will have two hours to solve six problems. After that you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

If you have ideas for some problems or maybe already prepared problems that you can't use in rounds or official competitions, you can write to me.

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Thanks a lot to Aleksa Plavsic allllekssssa who suggested several problems, two of them you will see on the round (the problems D and F). Also thanks to Bayram Berdiyev bayram, Allanur Shiriyev Allanur, Bekmyrat Atayev Bekmyrat.A. They are together suggested five problems, two of them you will see on the round (the problems B and E).

As usual the round was prepared by me, Edvard Davtyan. Thanks a lot to MikeMirzayanov we invented the problems A and C together. Also thanks to Maria Belova Delinur who will check English statements and Aleksa Plavsic allllekssssa who help me with problem testing and have constantly been in touch.

The first problem is pretty simple, so I'm waiting fast accepteds from you. The last problem is pretty difficult, so respect to all particiants who will solve it. I hope you will enjoy the problems!

Good luck and have fun!

UPD 1: I forgot to thank all other users who already sent me the ideas for the problems. I'll try to give that problems to the next rounds.

UPD 2: The main part of the contest is finished. The phase of hacks is started.

UPD 3: The editorial is ready.

UPD 4: The round is over, the results is final.