V.V. Khryashchev1, A.L. Priorov2, D.V. Matveev3, Yu.A. Lukashevich4

1–4 Yaroslavl State University named after P.G. Demidov (Yaroslavl, Russia)

1 v.khryashchev@uniyar.ac.ru, 2 andcat@yandex.ru, 3 diman@uniyar.ac.ru, 4 lukashevich.yuriy@gmail.com