I have been continously participating in contests for an year. I have been upsolving questions from contests too.Still I havent reached the level of solving D,E during contest(always due to some small problem) So now i want to ask what should be the way further to practise questions? 1. I have previously read practisiong tough questions is more important(We get ample practise of easy to moderate questions through contests). So how to filter questions?. The thing is if we select a very tough question then it's out of scope and we dont learn anything new and if we select too easy still we dont learn anything new? 2. Is codeforces the best website for practise or are there other websites with very good editorials,codes,filters etc. for practise? Thanks!!