Hello, Timus -

There is an interesting contest for Russian speaking participants.
You are suggested to solve 3 problems.
First problem is about bad network for maximum flow algorithm.
Second one is about king's placements on square chessboard.
Third problem is about 1-D walks and recurrences connected with it.

If you can read in russian, look at web-site:
http://zealint.ru/maxflow-kings-1dwalks-comp.html