I'm a student in Shenyang. I did the Beijing problem when I was reviewing for the senior high school entrance examination.
The problem in Beijing is very difficult!
But for your own future, you'd better study a few difficult problems.
Not quantity, but quality.
As long as you make five or six estimates carefully, you must
Make every step clear, so as to ensure that you
Have a plan, or you will have to do a lot of problems.
Also, communicate with teachers more.
I wish you good grades in the senior high school entrance examination!