what is the hardest part? so far i can play up to 3 lines after the things with the four chord things (with the squiggly, that you're not supposed to press all together as a whole but separetly but extremely fast) (but not so fast that you make it sound like its a whole) i want to get the hardest parts over with so that i can play and memorize the whole song.

The best way to figure out the hardest part for you is to play it the whole way through. Everyone has their hard parts and easy parts. What may be hard for one person might be a snap for someone else. Its a personal thing.