php if 2 files in dir unlink the olderst

1<?php
2    $directory = ".";
3
4    $files = array();
5    foreach(scandir($directory) as $file){
6        if(is_file($file)) {
7
8            //get all the files
9            $files[$file] = filemtime($file);
10        }
11    }
12
13    //sort descending by filemtime;
14    arsort($files);
15    $count = 1;
16    foreach ($files as $file => $time){
17        if($count > 10){
18            unlink($file);
19        }
20        $count++;
21    }
22