\documentclass{article}

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

\begin{document}

\pagestyle{empty}

\begin{tikzpicture}[
     level distance=1.5cm,
     level 1/.style={sibling distance=3cm},
     level 2/.style={sibling distance=1.5cm}
]
  \node[circle,draw]{root}
     child {
       node[circle,draw]{left}
         child {node[circle,draw] {lleft}}
         child {node[circle,draw] {rleft}}
     }
     child {
       node[circle,draw] {right}
         child {node[circle,draw] {lright}}
         child {node[circle,draw] {rright}}
     };
\end{tikzpicture}

\end{document}