I want to practice some previous year OI or ICPC regional problems, but most of them are obviously quite hard for me,can anyone suggest me some OI's/regional contests which I can start solving to improve at this level,or in other words what are some doable olympiads for a high expert or a low CM?
Try USACO problems (Silver/Gold is probably around your level).
Thanks for commenting, I am actually USACO gold,do you know any other competitions?