I am very much interested in Physics and Mathematics. I want some rigorous hard or tough competitions exam. I live in India so I want international exams and can be recognize everywhere in the world. The Exam should be International and I am doing by graduation currently. I want to participate in IMO and IPO but I miss the deadline for registering. Now I am 18 yrs old so I want to know how to take exams without college or school. Can IMO and IPO can be taken private, if so they what should I do. If cannot then suggest some others exam.