Latest pic at /b/

<?php
//Board address
$address = 'http://img.4chan.org/b';;

//RegExp Patterns
$PicPattern = '/\/src\/.+?.\.(jpg|png|gif|swf)/';
$ReplyPattern = '/res\/.+?.html/';

//Parse Threads from Boards first page
$page = file_get_contents("$address/imgboard.html");
preg_match_all($ReplyPattern, $page, $threads);

//Get picture URL:s from the first Thread
$page = file_get_contents("$address/" .$threads[0][0]);
preg_match_all($PicPattern, $page, $pics);
$lastpic = end($pics['0']);

//Echo result
echo "<img src='$address$lastpic' height='50%'>";
die();
?>

Now write it in lisp.