Adding adense code to template files!

How can I insert Adsense Ads into the template file so it appears in the Ist and 5th posts? I don’t want to insert it manually using the adsense deluxe plugin.

Here’s the template code of index.php (the loop)

<?php get_header(); ?>

<div id="content">

<?php include(TEMPLATEPATH."/l_sidebar.php");?>

	<div id="contentleft">

		<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
		<h1><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></h1>

		<div class="postmeta">
					<p><?php the_time('F j, Y'); ?> | Filed Under <?php the_category(', ') ?>&nbsp;<?php edit_post_link('(Edit)', '', ''); ?></p>
		</div>

		<?php the_content(__('Read more'));?><div style="clear:both;"></div>

				<!--
		<?php trackback_rdf(); ?>
		-->

		<?php endwhile; else: ?>

		<p><?php _e('Sorry, no posts matched your criteria.'); ?></p><?php endif; ?>
		<p><?php posts_nav_link(' — ', __('&laquo; Previous Page'), __('Next Page &raquo;')); ?></p>

	</div>

<?php include(TEMPLATEPATH."/r_sidebar.php");?>

</div>

<!-- The main column ends  -->

<?php get_footer(); ?>

Thanks in advance