Offline Exams Incoming

The excitement of physical college re-opening and the fear of offline exams incoming form a perfect couple, isn't it? Shivam has already finished backpacking, & he still has some time left before departure. He doesn't want to waste a single minute, so he thought to cover up his syllabus. There are $N$ coding questions in the book. The $i^{th}$ question belongs to $a_i$ topic. For having the bes