I have read a statement and tried to solve it. But I couldn't achieve it. Then when I opened this editorial I saw there is no solutions for problems D and E. This editorial was posted 2 years ago. Is he writing this two solutins for two years. I don't think so. This editorial isn't the only one. I think problem setters should write the editorials before the contest (without TODO's :) ) .In this way we will be able to learn solutions just after the contest. In my oppinion this is better. By the way sometimes there is no link to editorials from statements. This is a problem for me too.

I will be grateful if these problems solved.

Thank you...