There are two ways to practice: you can either take a virtual contest where you have five hours time to solve the problems (as in the original contest), or then you can upsolve the problems without limitations.
The contests have their original tests and subtasks (if specified in the problem statement). The time limits have been adjusted for the CSES contest system. All contests have full feedback.
If you have found errors or have other feedback, please send a message to firstname.lastname@example.org (Antti Laaksonen).