help with excerpt and content

<div id="shortcontent">
	<?php the_excerpt(); ?>
	<a href="javascript:void(0)" onclick="$('#shortcontent').hide();$('#fullcontent').show();">Show more</a>
</div>
<a href="javascript:void(0)"></a>
<div id="fullcontent" style="display: none">
	<?php the_content(); ?>
	<a href="javascript:void(0)" onclick="$('#fullcontent').hide();$('#shortcontent').show();">Show less</a>
</div>

Any ideas how to put this end of post? I want that link would be end of last sentence.