\documentclass{article}

\usepackage[T2A]{fontenc}
\usepackage[russian,english]{babel}
\usepackage[utf8]{inputenc}
\usepackage{amsmath,amssymb}
\usepackage{tikz}

\begin{document}

\pagestyle{empty}

\begin{tikzpicture}
  \draw[help lines] (0,0) grid (10,10);
  \foreach \x/\y/\n in {1/2/a, 4/5/b, 6/2/c}
    \node[circle,draw] (\n) at (\x,\y) {$\n$};
  \foreach \s/\t in {a/b, b/c}
    \draw[->] (\s) -- (\t);
  \draw (3,3) circle (40mm);
\end{tikzpicture}

\end{document}