problem displaying 3 level deep page hierarchy

Hi,
I have created page – “Solutions” , child pages of “Solutions – Design Solutions, Development Solutions & Mobile Solutions” and child pages of each, e.g. “Design solutions – 1. Web Design, 2. Print Design, 3. Logo & Identity, Development Solutions – 1. Web Development, … etc.
I want to show only last level pages i.e(web design, print design, web development,..) when I go to “Solutions” Page…
I tried the code, but it also shows the second level pages like Design Solutions and others. I want to hide them or exclude them, I also tried the wp_list_pages() and get_pages() but not working….
See the code…

if(have_posts()) : while(have_posts()) : the_post();

				$parents = get_pages('child_of='.$post->ID.'&parent='.$post->ID.'&hierarchical=0');
				//$mypages = get_pages('child_of=$parents&exclude=$parents')

				foreach($parents as $parent)
				{
					$parent_id[] = $parent->ID;
				}
				$value = implode(',', $parent_id);

				//$result = wp_list_pages('child_of='.$post->ID);

				$query = new WP_Query('post_parent='.$post->ID);

				while($query->have_posts()) : $query->the_post();
					the_title();
				endwhile;

….. so on…..

I also fetched IDs of those 3 posts and used it in parameters with exclude but didn’t work….

ANY SUGGESTIONS?