Error 505 single.php single post shown blank

i have modify single.php to ad Google adsense adv in single post but shown blak error 505 from mobile phone

how to fixed it?
plese help

i have add this code
<–<?php
$where = 0;
$content = apply_filters(‘the_content’, get_the_content());
$content = explode(“</p>”, $content);
for ($i = 0; $i <count($content); $i++) {
if ($i == $where) { ?>
<div style=”float:left; margin:0 10px 10px 0;“>

<script async src=”//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js”></script>
<!– 300 x 250 Kotak sedang bagus bwt mobile –>
<ins class=”adsbygoogle”
style=”display:inline-block;width:300px;height:250px”
data-ad-client=”ca-pub-4808730600143938″
data-ad-slot=”9147494008″></ins>
<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>

</div>
<?php
}
echo $content[$i] . “</p>”;
}
?>