Hi Codeforces! I'm currently training to go to the ICPC World Finals and after yesterday's Latin American Regional I realized something: I know nothing of Geometry!

Well to be fair, I know a few things here and there because of highschool and college, but my understanding of it is such a chaotic mess that I find it really to apply that limited knowledge in contests.

I'm trying to fix that but I don't really know how to start, so if someone could give me advice on how to start learning geometry from scratch and how to properly move on to harder things in competitive programming (geometry-wise) I would really appreciate it. Moreover, if you could recommend geometry books that you think could help me I would be even more thankful :)