I started solving problem A, let's say, around 00:18, but still not a problem.

After that, I had a really hard time on B, which I ended up solving at 00:46 in the contest. At that moment, I looked at my performance with the Carrot extension; I was performing like a 900 with a huge negative delta awaiting me.

I read C, spent some time on it, and couldn't come up with a solution.

Since I have an opinion that subtask problems like D1 and D2, the first one is usually easy to solve, I switched to it. Even with low constraints, I couldn't find a brute-force algorithm that worked. I got an idea of a sparse table and started coding it. After some hard time debugging, it passed the sample, and I submitted it 01:30. The green screen of Pretest passed was there, and I was happy.

I read D2 quickly and realized that my solution was the intended one for the full task and submitted it also, which got accepted at 01:31. (Still, I don't know how to solve D1 with a brute-force approach). At that moment, I was already well-ranked since even experts were on D1.

I moved back to C and got the idea in 5 min now. It passed pretest on 01:46.

Yeah, 1 hour back in the contest, I was having a performance of a newbie 900, and now I was performing close to a Candidate Master level. In the end, I will get a +140, which will bring me back to Specialist with 1493 as my rating.