Institute of Computer Science, Warsaw University of Technology, Warsaw, Poland.|Department of Computer Science, Poznan University of Technology, Poznaxc5x84, Poland.|Institute of Computer Science, Warsaw University of Technology, Warsaw, Poland.|Department of Computer Science, Poznan University of Technology, Poznaxc5x84, Poland.|Department of Computer Science, Poznan University of Technology, Poznaxc5x84, Poland.|Scientific IT Services, ETH Zurich, Zxc3xbcrich, Switzerland.|Institute of Computer Science, Warsaw University of Technology, Warsaw, Poland.