\begin{tikzpicture}[scale=2.54]%
% dpic version 2024.01.01 option -g for TikZ and PGF 1.01
\ifx\dpiclw\undefined\newdimen\dpiclw\fi
\global\def\dpicdraw{\draw[line width=\dpiclw]}
\global\def\dpicstop{;}
\dpiclw=0.8bp
\dpiclw=0.8bp
\dpicdraw[fill=black](0,0) circle (0.007874in)\dpicstop
\dpicdraw (0,0)
 --(0.25,0)\dpicstop
\dpicdraw (0.375,0.4375)
 --(0.625,0.4375)\dpicstop
\dpicdraw (0.875,0.4375)
 --(0.875,0.5375)
 --(0.625,0.5375)
 --(0.625,0.3375)
 --(0.875,0.3375)
 --(0.875,0.4375)\dpicstop
\draw (0.75,0.4375) node{$x_1$};
\dpicdraw (0.875,0.4375)
 --(1.125,0.4375)\dpicstop
\dpicdraw (0.375,0.0625)
 --(0.625,0.0625)\dpicstop
\dpicdraw (0.875,0.0625)
 --(0.875,0.1625)
 --(0.625,0.1625)
 --(0.625,-0.0375)
 --(0.875,-0.0375)
 --(0.875,0.0625)\dpicstop
\draw (0.75,0.0625) node{$x_2$};
\dpicdraw (0.875,0.0625)
 --(1.125,0.0625)\dpicstop
\dpicdraw (0.375,0.443056)
 --(0.375,0.056944)\dpicstop
\dpicdraw (1.125,0.443056)
 --(1.125,0.056944)\dpicstop
\dpicdraw (0.375,0.4375)
 --(0.375,0.4375)\dpicstop
\dpicdraw (1.125,0.4375)
 --(1.125,0.4375)\dpicstop
\dpicdraw (0.375,0.0625)
 --(0.375,0.0625)\dpicstop
\dpicdraw (1.125,0.0625)
 --(1.125,0.0625)\dpicstop
\dpicdraw (0.25,-0.25)
 --(0.375,-0.25)\dpicstop
\dpicdraw (0.625,-0.25)
 --(0.625,-0.15)
 --(0.375,-0.15)
 --(0.375,-0.35)
 --(0.625,-0.35)
 --(0.625,-0.25)\dpicstop
\draw (0.5,-0.25) node{$x_3$};
\dpicdraw (0.625,-0.25)
 --(0.75,-0.25)\dpicstop
\dpicdraw (0.75,-0.25)
 --(0.875,-0.25)\dpicstop
\dpicdraw (1.125,-0.25)
 --(1.125,-0.15)
 --(0.875,-0.15)
 --(0.875,-0.35)
 --(1.125,-0.35)
 --(1.125,-0.25)\dpicstop
\draw (1,-0.25) node{$x_4$};
\dpicdraw (1.125,-0.25)
 --(1.25,-0.25)\dpicstop
\dpicdraw (0.25,0.255556)
 --(0.25,-0.255556)\dpicstop
\dpicdraw (1.25,0.255556)
 --(1.25,-0.255556)\dpicstop
\dpicdraw (0.375,0.25)
 --(0.25,0.25)\dpicstop
\dpicdraw (1.125,0.25)
 --(1.25,0.25)\dpicstop
\dpicdraw (0.25,-0.25)
 --(0.25,-0.25)\dpicstop
\dpicdraw (1.25,-0.25)
 --(1.25,-0.25)\dpicstop
\dpicdraw (1.25,0)
 --(1.5,0)\dpicstop
\dpicdraw[fill=black](1.5,0) circle (0.007874in)\dpicstop
\end{tikzpicture}%

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