视频网站网址？

Question

I have a video site example: site.com/page5/ i have 5 page video.

But if I write url site.com/page50000000/ query returns.

<?
ob_start("ob_gzhandler");
include 'fonksiyon.php';
$say=mysql_query("select * from videos");
$saydim=mysql_num_rows($say);
$count = $saydim;
$perpage = 16;
$page = !empty($_GET["page"]) ? intval($_GET["page"]) : 1;
$s = ($page-1)*$perpage; 
$lastP = ceil($count/$perpage);
?>

I wanted do with header("Location:index.php"); with redirect to main page.

So if I write site.com/page100/, I want to redirect to my index.php, this is because I have 5 page video.