<?php    
highlight_file(__FILE__);
    @$k1=$_GET['key1'];
    @$k2=$_GET['key2'];
    if(@file_get_contents($k1)==="Hello hacker!"){
        echo 'welcome! Hacker!<br>';
        if(md5($k2)>666666*666666)
        {
            include('flag.php'); 
            @$k3=$_GET['key3'];
            @$k4=$_GET['key4'];
            if(intval($k3)<666)
            {
                if($k3==666)
                {
                    echo 'Come on, flag is coming<br>';
                    if($k4>0)
                    {
                        if(intval($k3+$k4)<666)
                            echo $flag;
                    }
                }
            }else{
                exit();
            }
        }else{
            exit();
        }
    }else{
        exit();
    }
?>