How to disable on only 1 url category please?

Hello I have found a working code to enable your plugin only on 1 url:

if($check_lg && !isset($_COOKIE['viewedExitPopupWP']) && $_COOKIE['viewedExitPopupWP'] != 'true' && strstr($_SERVER['REQUEST_URI'], 'fullscreen')) {

…but how to make the exact opposite? Load it on everywhere else but this “www.sitename.com/post/fullscreen” type of urls?

Thank you very much!