Aaaand another editorial that is clear as mud. Sigh. You would have hoped SOME effort would go in to writing, but once more I see a kind of 'look how clever I am such that this is so obvious to me' style of writing :(

is this a medium one? even have no idea. so weak i am.

What are the fundamentals I should learn and practice before particiapating these level of contests. I am a beginner in programming having basic knowledge on DS and OOPS concepts. I was excited to take part in this contest, but after reading questions.. I am totally blank

I am totally blank for this question O_O

I hope the editorial explains the solution in detail (for newbies like me to understand ^_^)

Wow, look at that success rate...