简单的反序列化代码，请尝试获取flag
<?php
    class z {
        public $a;
        function __toString(){
            return $this->a->b['a'];
        }
    }
    
    class c {
        public $method;
        function __call($method,$arg){
            var_dump($arg);
            if(in_array($method, $this->method)){
                eval(array_shift($arg));
            }
        }
    }
    
    class q {
        public $z;
        public $f;
        public $arg;
        function __get($p){
            $this->xixi=clone $this->z;
            return "haha";
        }
        
        public function __clone() {
            return $this->f->haha($this->arg);
        }
    }
    
    if (isset($_GET['Str'])){
        echo unserialize($_GET['Str']);
    }else{
        highlight_file(__FILE__);
    }
?>