This is the D question of this year's Mathematical Modeling Competition. If you can write the answer clearly here, there will be no contest.

In addition, there is no standard answer to the mathematical modeling contest. You'd better try to do it yourself.

Try to digitize the favorable and unfavorable factors that we usually think as much as possible and turn them into mathematical symbols. We must write our mathematical model clearly in the paper. You can't just have data and tables without models, so you won't get the prize.

No one has studied this problem because our school does not participate in special group competitions. I hope you can get good grades.