C 1 is mainly algebra, quadratic equation, equality and inequality, coordinate geometry, sequence and series, arithmetic progression (studied in senior one and senior two in China), differential and integral. The calculus of C 1 is super simple.
C2, algebra, coordinate geometry (these two junior high schools also need to learn), sine and cosine formulas, logarithm and exponent, binomial expansion, geometric series, radian, trigonometry and calculus, which may not be formally touched in junior high school, but I think it is not difficult, almost at the junior high school level.
S 1 is the first book of statistics, and it is not difficult to listen and speak. M 1 is the first book on mechanical mathematics, kinematics, statics and dynamics. You only need to remember a few ultra-simple formulas. D 1 listening and speaking is also simple. Generally, one of these three books is accompanied by C 1 and C2.
Different examination committees may study in different order, but as a whole, that's all.
If you think your math is not bad and you are interested in it, it is not bad to continue studying math.