Since nobody posted this...
Tasks are here: https://ioi2021.sg/ioi-2021-tasks/
You can solve all Day 2 tasks here: https://oj.uz/problems/source/577
In case you want to solve it in 5 hours, you can try here: https://oj.uz/contest/view/IOI2021DAY2
- Related post: https://codeforces.net/blog/entry/92088