<?php

error_reporting(0);

if (isset($_GET['cmd'])) {
    $cmd = $_GET['cmd'];

    if (preg_match("/flag|cat|ls|echo|php|bash|sh|more| |less|head|tail|[\|\&\>\<]|eval|system|exec|popen|shell_exec/i", $cmd)) {
        die("Blocked by security filter!");
    } else {
        eval($cmd);
    }
} else {
    highlight_file(__FILE__);
}
?>

<?php
error_reporting(0);

class Flag {
    private $flag;

    public function __construct() {
        $this->flag = file_get_contents('/flag');
    }

    public function getFlag() {
        return $this->flag;
    }

    public function __toString() {
        return "You can't directly access the flag!";
    }
}

class User {
    public $username;
    public $isAdmin = false;

    public function __construct($username) {
        $this->username = $username;
    }

    public function __wakeup() {
        if ($this->isAdmin) {
            echo "Welcome, admin! Here's your flag: " . (new Flag())->getFlag();
        } else {
            echo "Hello, " . htmlspecialchars($this->username) . "!";
        }
    }
}

if (isset($_GET['data'])) {
    $data = $_GET['data'];

    $object = unserialize($data);
    if ($object instanceof User) {
        echo $object;
    } else {
        echo "Invalid object!";
    }
} else {
    highlight_file(__FILE__);
}
?>

<?php
error_reporting(0);
highlight_file(__FILE__);
$a = "isctf2024";
$b = $_GET["b"];
@parse_str($b);
echo "小蓝鲨开始闯关，你能帮助他拿到flag吗?<br>";
if ($a[0] != 'QNKCDZO' && md5($a[0]) == md5('QNKCDZO')) {
    $num = $_POST["num"];
    echo "第一关有惊无险！小蓝鲨壮着胆子接着继续往下走！<br>";
    if($num == 2024){
        die("QAQ小蓝鲨误入陷阱，不怕，再接再厉！");
    }
    if(preg_match("/[a-z]/i", $num)){
        die("陷阱太多QAQ");
    }
    if(intval($num,0) == 2024){
        echo "到这了难道还要放弃吗？<br>";
        if (isset($_GET['which'])){
            $which = $_GET['which'];
            echo "小蓝鲨貌似在哪里见过这个陷阱O.o?继续加油，还差最后一步了！";
            switch ($which){
                case 0:
                    print('QAQ');
                case 1:
                case 2:
                    require_once $which.'.php';
                    echo $flag;
                    break;
                default:
                    echo GWF_HTML::error('PHP-0817', 'Hacker NoNoNo!', false);
                    break;
            }
        }
    }
}