First and last post in loop

for the last post per page, before this line <?php else : ?> add an ‘elseif’ section;

<?php elseif($c == $wp_query->post_count) : ?>
<!--//HOW TO SHOW LAST POST ON PAGE//-->

ps:

for the last post only on the last page:

<?php elseif( ($wp_query->current_post+1 == $wp_query->post_count) && ($wp_query->max_num_pages == get_query_var('paged')) ) : ?>
<!--//HOW TO SHOW LAST POST OF ALL POSTS//-->

It works but last post is shown 2 times.

<?php if (have_posts()) : ?>
<?php $post = $posts[0]; $c=0;?>
<?php query_posts( 'posts_per_page=8&cat=13' );?>
<?php while (have_posts()) : the_post(); ?>

<?php $c++;
if( !$paged && $c == 1) :?>

            <div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
                <div class="post-entry">
                    <?php if ( has_post_thumbnail()) : ?>
                        <a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>" >
                    <?php the_post_thumbnail(); ?>
                        </a>
                    <?php endif; ?>
	<h1><a href="<?php the_permalink() ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a>
	<?php edit_post_link(__('<img src="' . site_url('') . '/wp-content/themes/default/icons/edit.png" />', 'default')); ?>
	</h1>
					<?php the_content(''); ?>
                </div><!-- end of .post-entry -->

            </div><!-- end of #post-<?php the_ID(); ?> -->
		<div class="post-titles">

	<?php elseif($c == $wp_query->post_count) : ?>

	<h2 class="last"><a href="<?php the_permalink() ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a>
	<?php edit_post_link(__('<img src="' . site_url('') . '/wp-content/themes/default/icons/edit.png" />', 'default')); ?>
	</h2>
	    <?php else : ?>
	<h2><a href="<?php the_permalink() ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a>
	<?php edit_post_link(__('<img src="' . site_url('') . '/wp-content/themes/default/icons/edit.png" />', 'default')); ?>
	</h2>

		<?php endif;?>

		<?php endwhile; ?> 

<?php endif; ?>

All okey, I made mistake! Thanks! ??