The difficulty is only relative. If you study hard, you are sure to have no problem. In fact, advanced mathematics is an extension of high school mathematics, such as integral. In high school, it was 1+ 1=2, and in college it was 2- 1= 1. Of course, this is a general metaphor. Look at the examples, the high number can be about 85! If you don't learn, I believe that no matter what difficulties!