This is the fourth week of Vincent Massey's Seven Week Challenge! In the seven weeks leading into CCC, we'll be writing weekly contests to prepare everyone for it. Each contest will have three problems, in order of difficulty: Bronze, Silver, and Gold. You'll have a week to solve them all, so take it easy.

This week's problem writer is DianaC! In this contest, you'll be assisting JeffreyZ in his journey to create great test cases. Bronze and Silver should be solvable with Python. Gold was done in C++ and I'm not going to make any guarantees about that one, although it should be doable with Python with an efficient algorithm. All of the problems should be fairly straightforward with Gold being a little bit harder than last week.

I'd like to thank JeffreyZ for letting me use his name in this contest and for being the inspiration for the questions. You will find that my test cases are not better than his, if not worse. I'd also like to thank DMOJ problem coordinator cheesecake for allowing us to host the 7WC on DMOJ.

This round will be unrated.

Before the contest date, you may wish to check out the tips and help pages.

The contest consists of three problems with a difficulty range similar to that of CCC Junior. If you cannot solve a problem fully, we encourage you to go for partial marks.

After joining the contest, you proceed to the Problems tab to begin. You can also go to Users if you wish to see the rankings.

We have listed below some advice as well as contest strategies:

• Start from the beginning. Ties will be broken by the sum of times used to solve the problems starting from the beginning of the contest. The last submission time of your highest score will be used.
• Remove all extra debugging code and/or input prompts from your code before submitting. The judge is very strict — most of the time, it requires your output to match exactly.
• Do not pause program execution at the end. The judging process is automated. You should use stdin / stdout to perform input / output, respectively.
• It is guaranteed that all the problems will be solvable with C++.

Don't panic. Good luck!