For the fourth time, the International Informatics Olympiads in Teams will be mirrored into online contests. These contests, of a lower difficulty level than those of the IOI, are intended for teams of 4 contestants from the same high school. However, everyone is welcome to participate to the mirror contests, especially if you are considering to join officially the IIOT in the future!

More specifically, we allow:

• several teams from the same school (also in the official contest)
• teams participating only in some contests (also in the official contest)
• changes in team members
• teams of students from different schools
• smaller teams

The mirror contests timing will be USACO-like: it will be open for 24 hours but you will be able to compete for up to 3 hours (you can decide when to "start" your time window, after the login). Participation will be available upon registration (re-registration needed for each contest). The problem statements will be available in English only, and the languages allowed are C, C++, Pascal and Python 3. Every contest will consist of 8 or 9 problems (see https://iio.team for further information).

Note: you can decide when to start your 3 hour time window, but remember that the contest will end 24 hours after the start of the official contest regardless of your time window!

If you want to participate, you must:

1. Visit the contest website: https://mirror.squadre.olinfo.it/
2. Click the link "register", fill out the form and then click on the register button and then "back to login"
3. You can now log in with the same username and password you used to sign up
4. If the login is successful you will be ready to participate, just wait for the contest to start! (and maybe save the page in your bookmarks, so that you can quickly get back to it when the contest begins)
5. When the contest starts, you will see a red button. Click it when you want to start your 3 hour time window!
6. The ranking for each contest will be available at https://mirror.squadre.olinfo.it/ranking/ after the start of each contest
7. The tasks will also be available for training in https://training.olinfo.it few days after the contests
8. Good luck and have fun!

The schedule of the contests is the following (starting times in the CET time zone):

• Round 1: nov. 16 @ 14:30
• Round 2: dec. 15 @ 14:30
• Round 3: jan. 13 @ 14:30
• Round 4: feb. 4 @ 14:30
• Finals: feb. 26 @ 13:00

We hope that you will join us or encourage your students to do so!

Giorgio Audrito (on behalf of the Italian IIOT organizers)