1. V. I. Romanovskiy Institute of Mathematics, Uzbekistan Academy of Sciences, 9, University Street, Olmazor District, Tashkent, 100174, Uzbekistan
2. National University of Uzbekistan, 4, University Street, Olmazor district, Tashkent, 100174, Uzbekistan
3. V. I. Romanovskiy Institute of Mathematics, Uzbekistan Academy of Sciences, University Street, 9, Olmazor district, Tashkent, 100174, Uzbekistan
4. Department of Mathematics, Karakalpak State University, 1, Ch. Abdirov, 230112, Nukus, Uzbekistan
5. Department of Mathematics, Nukus state pedagogical institute, 1, P. Seyitov, 230105, Nukus, Uzbekistan