<?php
if (isset($_GET['ad']) && $_GET['ad'] == 1)
{
echo "";
}
else {
echo '<div class="ad-area"><p>This is the ad, click here</p> </div>';
}
?>

<input type="hidden" name="link" value="<?php echo $linkk; ?>?kw=<?php echo $_GET['kw']; ?>" />

echo '<input type="hidden" name="link" value="'.$linkk.'?kw='.$_GET['kw'].'" />';