For the second time (part1) enjoy two videos by me and SecondThread.

• My old problem 611F - New Year and Cleaning we discuss on his channel https://youtu.be/gmdBav_Nuuc
• Facebook Hacker Cup R3 problem B. Railroad Renovations on my channel https://youtu.be/2FlVv4acc2g

I hope you like this format of taking an old cool problem and just discussing it.