Capture the flag (CTF) write-ups NPST 2020 https://blog.roysolberg.com/2021/01/pst-challenge-5 2019 https://blog.roysolberg.com/2020/01/pst-challenge-3 PHST 2020 https://blog.roysolberg.com/2020/04/pst-challenge-4 PST job ads 2019 https://blog.roysolberg.com/2019/10/pst-challenge-2 https://blog.roysolberg.com/2019/01/pst-challenge RSXC 2023 ./rsxc-2023/ 2021 ./rsxc-2021/