The text is incorrect:

"...to present it by the set of pairs of adjacent edges..." means not to transform the graph into a form in which it will be unequivocally presented by the set of pairs of its adjacent edges (it is rather difficult problem), but only to share (divide, separate) it into pairs of adjacent edges (it is easy).

i.g. you can divide graph [1-2-3-4-1] into [1-2] and [3-4]

Text is correct.

One can understand this problem with a help of simple example:
Imagine graph drawn on a wall. Select any vertex and erase exactly two edges incidental to this vertex. The question of problem is:  "Is it possible to erase all edges of graph doing in this way?".

The text is
"There is a simple graph with an even number of edges. You are to define if it is possible to present it by the set of pairs of adjacent edges (having a common vertex)."
Isn't it?

It differs from
"Imagine graph drawn on a wall. Select any vertex and erase exactly two edges incidental to this vertex. The question of problem is: "Is it possible to erase all edges of graph doing in this way?""
Isn't it?

I've understood the real definition, 'cause I was on quaterfinal, and I still think that the text doesn't correspond this definition. Text should be changed. It's easy.
Isn't it?

I think statement is correct. I also was at quarterfinal, but understand problem in right way.

I was in jury of that quarterfinal, so I know this problem better.

I doubt problem text will be changed, because union of original text and clarification text (about graph on a wall) should be enough to solve this (easy) problem.

Too lazy to change or too stubborn to recognize a mistake?
So now everyone who wants to solve this problem and was not in jury of that quarterfinal should get WA several times and then come to the board and see your "clarification"? By the way, do you know why this ("easy") problem has only 11% of AC?

>Too lazy to change or too stubborn to recognize a mistake?
Mostly: jury is very tired. There were no questions on this issue on contest, so text is OK.There are questions at timus - and they are answered.

Anyway, before throwing such words ("lazy", "stubborn", "mistake") you should organize couple of quarterfinals (for example next quarterfinal) yourself. All question to jury of this particular contest should be posted
to contest.ur.ru/board/

>By the way, do you know why this ("easy") problem has only 11% of AC?
Here "easy" means "has simple solution" but not "is obvious".

>Anyway, before throwing such words ("lazy", "stubborn", "mistake") you should organize couple of quarterfinals (for example next quarterfinal) yourself.

Really? So I will take your word for it. I am ready to do it. In fact, I've thought about organizing 1/8 final zone, but I was not sure it is possible. And now such an opportunity! Thank you very much. Mail me to dimanyes@mail.ru for next discussing.

To everyone: Mr. Mironenko wants me to organize next quaterfinal. So, welcome next year to Dmitry "Diman_YES" Kovalioff's Quaterfinal in Tyumen!

Actually I didn't understand problem statement either. I don't like going to the boards before solving a problem because sometimes the solution is spoiled. In this particular case if you don't GUESS what the problem statement means you HAVE TO come to the board.