<map id="C" name="C">
<area shape="rect" id="node1" title=" " alt="" coords="18,95,57,121"/>
<area shape="rect" id="node3" href="$class_d.html" title=" " alt="" coords="50,184,89,211"/>
<area shape="rect" id="node2" href="$class_a.html" title=" " alt="" coords="76,5,114,32"/>
<area shape="rect" id="node4" href="$class_b.html" title=" " alt="" coords="133,95,172,121"/>
</map>
