LaTeX in Russian

\documentclass{article}
\usepackage[T2A]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[russian]{babel}

\begin{document}
\selectlanguage{russian}
\textit{Primer teksta na russkom yazyke.}
\end{document}

\documentclass{article}
\usepackage{fontspec}
\usepackage{polyglossia}
\setdefaultlanguage{russian}
\setmainfont{Times New Roman}

\begin{document}
\selectlanguage{russian}
\textit{Primer teksta na russkom yazyke.}
\end{document}