Hello, welcome to a non-regular DMOJ contest. We're glad to invite you to the Double Doors Regional! The contest duration is 3 hours. This round will be rated for all participants who submit at least once.

The contest writer is suchaHassle, and the contest testers are goffrie, ksun48, lg52931, LiChenKoh, xiaowuc1, and y0105w49. Do not miss the round!

This contest will feature six problems of varying difficulties. The contest writers have attempted to sort the problems roughly in increasing difficulty order, though you are recommended to read through all of the problems.

The contest will run on a pretest/systest format. The contest writers intend for the pretests to be comprehensive and cover the full test suite, but retain the right to augment the test data in the event contestants attempt to exploit the data provided. Contestants are limited to 50 submissions per problem.

Unlike with other contests, there will be no partial credit for any of these problems. Furthermore, all problems will be graded with an identical checker. The judges will provide links to sample input and output files for contestants to diff against. The contest will follow the standard convention of having all lines terminate in a \n character. For those doing the contest on Windows machines, note that the sample files are not formatted for Windows and will therefore not have \r characters.

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 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. Questions which are not yes/no questions will be immediately closed with an Invalid Question comment.

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

The contest consists of 6 questions with a range of difficulty from CCC Junior through CCC Senior. It is highly recommended to read all of the problems. You will have 3 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 3 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 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 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 Java.

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.