You have an exam but not confident about yourself… then work for it. Yeah some might be blessed with extra talent.. some might be smart some might be witty but my friend nothing is impossible if you believe in yourself.
Set your goal, work for it and make sure not even a single negative comment let you set aback. If not you who can believe in yourself then who can ?
Just keep working till you get where you want yo be. It doesn’t matter if you are unable to fly, try running, if not running then try walking, if not walking then try crawling.. just keep moving and noy settling down. There is no failure .. it is either you succeed or learn. You all are unique and have all what it takes to achieve it. Just beleive in yourself.