In yesterday's contest Codeforces Round 865 (Div. 1) I've got the achievement which I could not imagine just half a year ago — reach 2400 rating and become GM.

The first time I learned about CF was on 2022.2, that time I registered this account and took my first contest. But my first submission 146390589 on contest got TLE, and I solved 0 problem in this contest. (At that time I didn't know that's because the efficiency of java.util.Scanner is extremely low) And because I needed to deal with graduation thesis, I didn't use CF until the end of last year, when I restarted CF contest.

At 4th and 5th contests I solved div2D problems to reach blue. In my 9th contest, I first time solved div2E problem in contest, and I became purple in my 12th contest. In my 14th and 15th contest, I solved div2E problems twice and became orange. In the next weeks, I started to hit the upper limit of my skill, and dropped from orange twice.

In order to improve my skill of competive programming, I practiced problems in CF problemset everyday, and when practicing I tried to solve every problem with 2000-2500 difficulty by the reverse order in the problemset. I took part in every rated CF contest (except Codeforces Round 856 (Div. 2) which was timed at 01:35 UTC+8), and learned many new techniques from problems I could not solve in contests. I also used other CP platfroms like atcoder, where I've reached rating 2233.

It seems that practice was pretty effective for me. I got well performance in last 3 contests rated for div1, and first time became red yesterday. Although there's still a large promotion space for me, it's an important meaningful moment in my life of competitive programming. Hope that I will be more active to face the challange in the future.