<?php
$adv = array(
    'dyn'    => 'adv.php', 'stat'        => 'addstatlink.php',
    'banner' => 'addbanner.php', 'mails' => 'addpmails.php',
    'task'   => 'addtask.php'
);

if(isset($_GET['adv'], $adv[$_GET['adv']])) {
    require $adv[$_GET['adv']];
}