\documentclass{standalone}

\usepackage{tikz}

\begin{document}
\begin{tikzpicture}[thick]

\draw[very thick] (-1,3.5) -- (-1,-0.5) -- (1,-0.5) -- (1,3.5);

\begin{scope}
    [every node/.style={
        rectangle,draw,minimum width=18mm,minimum height=8mm}]
    \node at (0,0) {81};
    \node at (0,1) {45};
    \node at (0,2) {14};
    \node[dashed] at (0,5) {11};
    \node[dashed] at (0,6) {0};
\end{scope}

\draw[->] (0,3.4) -- node[right] {push} (0,2.6);

\end{tikzpicture}
\end{document}
