Hello, welcome to a DMOJ contest! We're glad to invite you to another contest! Here are the parameters of the contest:

• Contest duration: 1.5 hours.
• Number of problems: 4, full feedback. Each problem is worth one point.
• There will be an interactive problem.
• This contest was run with a rating ceiling of 2199 under the legacy TopCoder rating system.
• Scoreboard will be hidden.
• Contest will run on AtCoder format. This means that ties will be broken first by the number of points you have, and second by the time of your latest first AC on a problem, plus five minutes per non-CE wrong submission prior to getting first AC on a problem.
• Number of submissions allowed per problem: Unlimited.
• Checkers for problems: Unless otherwise specified, identical. The contest will follow the standard convention of having all lines terminate in a \n character.
• Testers for this contest: arknave, dawnstar63, gs14004, Pookmeister, Riolku, and y0105w49.

Clarification requests for the contest must be routed through the clarification system provided on DMOJ, and not through other channels including but not limited to Discord, Messenger, or Slack. Furthermore, all clarification requests will be handled the way they normally are in IOI. Note that, in particular, clarification requests must come in the form of yes/no questions. Responses to questions will consequently be one of the following:

• Yes.
• No.
• Answered in task description (explicitly or implicitly).
• Invalid question.
• No comment.

Due to rampant issues with cheating on contests that has happened recently, any suspicious behavior during the contest window may result in your performance being disqualified and pushed to the bottom of the scoreboard. Such behavior includes, but is not limited to:

• Registering for the contest with at least two accounts.
• Participating in the contest with an account that is not one's primary account.
• During the contest window, talking about the contest in more detail than answering a yes/no question about whether one participated in the contest.
• Attempting to exploit bugs in the platform to subvert the constraints of the contest.

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

The contest consists of 4 questions with a range of difficulty. It is highly recommended to read all of the problems. You will have 1.5 hours to complete the contest. After the contest window begins, you may begin at any time. Your personal timer will start counting down, and you will be able to submit until 1.5 hours from when you started, or until the hard deadline, whichever comes first.

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 as specified at the top of the contest description.
• Remove all extra debugging code and/or input prompts from your code before submitting. The judge is strict — your output must match the judge output 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 Python 3. All problems have a time limit of at least 1.5x the reference solution, which is written in Python 3 (note that this is not using PyPy3, which we do not guarantee is a viable language to solve every problem in).

At the end of the contest, you may comment below to appeal a judging verdict. In the case of appeals, the decision(s) of our staff is final.