I am participating presently in the September 2020 Long Challenge - Division 1, and I have been using Ideone.com editor for writing the solutions.
I have just noticed that the visibility of the first two problems have been made public by some error or mistake. I always keep the visibility secret when using Ideone.com, and I have no idea how this default setting has been changed.
I have already restored the secret visibility of the solutions, and I do hope that ALL participants are fair enough to solve the problems independently, and to not use such incidents to ruin the contest.