1. Faculty of Mathematics and Computer Sciences Named after Prof. Nikolay Chervyakov, North-Caucasus Federal University, 355017 Stavropol, Russia
2. Control/Management and Applied Mathematics, Ivannikov Institute for System Programming, 109004 Moscow, Russia
3. North Caucasus Center for Mathematical Research, North-Caucasus Federal University, 355017 Stavropol, Russia
4. Mathematics Department, Faculty of Education, University of Misan, Amarah 62001, Maysan, Iraq