<map id="C" name="C">
<area shape="rect" id="node1" title=" " alt="" coords="37,95,76,121"/>
<area shape="rect" id="node3" href="$class_d.html" title=" " alt="" coords="68,184,106,211"/>
<area shape="rect" id="node2" href="$class_a.html" title=" " alt="" coords="98,5,137,32"/>
<area shape="rect" id="node4" href="$class_b.html" title=" " alt="" coords="156,95,194,121"/>
</map>
