Happy New Year everyone !
I want to direct your attention to tutorials . They are not as detailed as they are needed . Last contests' tutorials (Good bye & CR#221) look like written in 30 minutes . Some of problems are explained well , but others are hard to understand even after reading more explanation in comments . For example : "221 Div1 C" & "Good Bye E" tutorials of this problems are just hints in my opinion .
I want to ask authors of this problems to update tutorial and write it more detailed . I am lazy to analyze other contestants' codes as they are in writing tutorials .