window ac unit - extension cord or surge protector?

Hi, I'm a college student living in the US for the first time. I am not really used to window acs because they have built in ceiling ones where I come from !

I was wondering if I should use a heavy duty extension cord(from amazon, said for window ac units specifically) or a surge protector.
I hear some say plug directly into the wall with extension cord, and i also hear use surge protector.

So i am a little confused on which I should do. Any advice?

My ac is a 5000btu by the way.