1. Department of Probability Theory, Statistics and Actuarial Mathematics, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
2. Department of Probability Theory and Mathematical Statistics, Faculty of Mathematics and Information Technology, Vasyl Stus Donetsk National University, Vinnytsia, Ukraine
3. Department of Physical and Mathematical Disciplines, Uzhhorod National University, Uzhhorod, Ukraine