I noticed that most of the red coders in codeforces entered many Div2 contests at the beginning which made me assume that if I entered many Div2 contests and learned from the solutions of the problems that I couldn't solve that my performance shall go better. But when I entered a Div2 contest I solved 0 problems , I learned from the solutions in the editorial after then, but this made me ask if shall I participate in Div3 contests for sometime before entering the Div2 contests or shall I continue? For the Div3 contests I can solve some of their problems but at Div2 contests most of the time I can solve none of them in the timeframe of the contest, may be if I tried to solve each of them separately without a timeframe I can but it will take from me long time maybe several hours for each problem. Also I want to ask if training from the contests is the idea technique or shall I learn the topics separately and search for it's problems and if this is the right way for learning is there any reference that tells the order of the sub-topics of each topic to follow in the learning process?