What are the Mathematical prerequisites for understanding Algorithms?

I watched some lectures on YT and well Theres so much on algorithms analsis asymptotic analysis, t(n), big o, big omega, run time, functions(only this I understand), what math do I have to take to understand these, is it Discrete Mathematics_?, Im asking this because Im thinking about studying CS but men that algorithm analysis seems really hard, Is it really hard though_? and again what math do I need, pleeease and thanks