Hardest school subect you''ve ever studied?

Back in my "high school" days I had troubles with history. I do like the course but it didn't matter how much I studied for it, I didn't seem to get a lot higher than a 5/10 (I'm from the Netherlands and we get scores on a scale from 0-10 instead of A,Bs etc. So I dropped the course after year 4 out of the 6 years "high school/ VWO". Nowadays in my study I usually have troubles with law courses.

~Greetings PJ!