Happy Halloween! We're glad to invite you to an annual evaluation of logic and programming! Here are the parameters of the contest.

• Contest duration: 24 hours.
• Unrated.
• Scoreboard will be public. Ties will be broken by the time of the last score-increasing submission.

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

It is highly recommended to read all of the problems. You will have 24 hours to complete the contest.

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 last score-increasing submission time starting from the beginning of the contest.
• 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.