Welcome to yet another Yet Another Contest!

The problem setters are Josh and RandomLB.

Thanks to Snowfall, 4fecta, jeroenopdebeek, thomas_li, LogicXD and andy_zhu23 for testing, feedback, and assistance with the problems!

Special shout-out to Riolku and Nils_Emmenegger for helping us organize the contest!

The contest will be rated for all participants with a rating under 2800.

Additionally, this contest has prizes courtesy of c! Specifically:

• The winner of the contest, including unrated users, will win one month of Discord Nitro.
• The two highest placing rated users will win one month of Discord Nitro Basic. If the overall winner was rated, then the next two highest placing rated users will win Discord Nitro Basic.
• Steam codes will provided to a user selected uniformly at random from the top 100, excluding users who have already won prizes. These codes are for Sid Meier’s Civilization VI, and includes six scenario packs.

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

This contest will consist of 6 problems, the difficulty of which may range anywhere from CCC Junior to CCO level.

You will have 3 hours to complete the contest. After the contest window begins, you may begin at any time. Once you enter the contest, your personal timer will start counting down and you will be able to submit until 3 hours from when you started, or until the hard deadline (00:00:00 EST of December 27th), whichever comes first.

After joining the contest, you proceed to the Problems tab to begin.

Here are the parameters of the contest:

• Some problems offer partial marks in the form of subtasks. Specifically, for problems with subtasks, batch dependencies will be structured as follows: if the set of cases possible for a subtask B is a superset of the cases for a previous subtask A and any case in A produced a non-accepted verdict, the cases in B will not be executed. These dependencies will not be noted in the problem statements.
• Number of problems: 6, full feedback (you will see the results of your submissions instantly).
• Number of submissions allowed per problem: 50.
• Scoreboard will be hidden, until your window is over. Divulging the contents of the scoreboard to participants who have not finished their window is an offense, the punishments of which are listed below.
• Ties will be broken by the maximum submission time that increased score with no penalties.
• Problems will be approximately increasing in difficulty, and will all have full feedback. Reading all of the statements is recommended.
• Rated for opening the contest. Being able to read the problems will cause the contest to be rated.
• Checkers: unless otherwise specified, standard.
• Interactors: unless otherwise specified, assume that all interactors are not adaptive.
• It is guaranteed that all problems will be solvable with C++.

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

• 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.
• Python users are recommended to use PyPy 2/3 over Python 2/3 when submitting, unless otherwise specified.

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 and 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.

Due to rampant issues with cheating on contests that has happened recently, any suspicious behavior during the contest window may result in your rating being impacted negatively. Such behavior includes, but is not limited to:

• Divulging the contents of the scoreboard to participants who have not finished their window.
• Registering for the contest with at least two accounts.
• Participating in the contest with an account that is not your 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. This includes, but is not limited to, posting spoilers about the contest and public speculation of the contest.
• Attempting to exploit bugs in the platform to subvert the constraints of the contest.
• Attacking the judge infrastructure, other contestants, or contest personnel within or after your window.

Punishments may include performance being unrated or, for more serious infractions, being forcibly ranked at the bottom of the scoreboard.

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