The typical preamble of a LaTeX file with the Russian language is:

\documentclass{article}
\usepackage[T2A]{fontenc}
\usepackage[koi8-r]{inputenc} % adjust your enconding here
\usepackage[russian]{babel}
\usepackage{nm}

The nm package defines additional LaTeX commands:
\ruble for the Russian ruble sign;
\ellipsis for the alternative variant of ellipsis.