Well, this is weird. If you do not include complex answers this problem is very easy. But complex numbers aren't taught before college, at least where I live. And for college level it's still not difficult, so what Olympiad is this from? :)
Olympiad questions are supposed to be "above average difficulty." If you see an easy question labeled "Olympiad," it's a lie. Think of Olympiad as questions that might be taught in AP Math in high school.
