一個CTF GAME引發的php內核分析

<?php
   error_reporting(0);
   require __DIR__.'/lib.php';
   if(isset($_GET['time'])){
       if(!is_numeric($_GET['time'])){
           echo 'The time must be number.';
       }else if($_GET['time'] < 60 * 60 * 24 * 30 * 2){
           echo 'This time is too short.';
       }else if($_GET['time'] > 60 * 60 * 24 * 30 * 3){
           echo 'This time is too long.';
       }else{
           sleep((int)$_GET['time']);
           echo $flag;
       }
       echo '<hr>';
   }
   highlight_file(__FILE__);

<?php
echo 60 * 60 * 24 * 30 * 2;
echo "/n";
echo 6e6;
echo "/n";
echo (int)'6e6';
echo "/n";
echo 60 * 60 * 24 * 30 * 3;

5184000
6000000
6
7776000