1. Faculty of Science, University of Hradec Králové, Rokitanského 62, 500 03 Hradec Králové, Czech Republic
2. Sobolev Institute of Mathematics, 630090 Novosibirsk, Russia
3. Laboratory of Dynamical Systems and Applications, National Research University Higher School of Economics, ul. Bolshaya Pecherskaya, 25/12, Nizhny Novgorod 603155, Russia