найти ошибку в php коде

<?php
$fexists='freebanner/count.txt';
if(file_exists($fexists)){
$linecount = count(file('freebanner/bannera.txt'));
$rand = rand(0,$linecount-1);
$text=file('freebanner/bannera.txt');
$banner = $text[$rand];
 
$site=file('freebanner/url.txt');
$siten = $site[$rand];
 
$count=file($fexists);
$countn = $count[$rand];
if (($countn!=1)and ($countn!=null)and ($countn!=0)) {
 
$rand = rand(0,count($count)-1);
$count[$rand] = ($count[$rand]-1).PHP_EOL;
if($count[$rand] < 1)
unset($count[$rand]);
file_put_contents($fexists,$count);
echo '<div class="pod240">
<a target="_blank" href="'.$siten.'">
<img src="'.$banner.'" width="240" height="400">
</a>';
echo '<a style="text-align:center;line-height: 15px;text-decoration:underline; margin-top:-4px; width:240px; height:16px; display:block; background: #FFB366;" href="freeadvert.html"><b>размещение рекламы за баллы</b></a></div>';
}
if (($countn<=1)or($countn==null)) {
$imya_faila = "freebanner/bannera.txt";
$fail = file($imya_faila); 
unset($fail[$rand]); 
$fp = fopen($imya_faila, "w"); 
fputs($fp, implode("", $fail)); 
fclose($fp);
$imya_faila = "freebanner/count.txt";
$fail = file($imya_faila); 
unset($fail[$rand]); 
$fp = fopen($imya_faila, "w"); 
fputs($fp, implode("", $fail)); 
fclose($fp);
$imya_faila = "freebanner/url.txt";
$fail = file($imya_faila); 
unset($fail[$rand]); 
$fp = fopen($imya_faila, "w"); 
fputs($fp, implode("", $fail)); 
fclose($fp);
 
}
}
?>

ini_set();