Always fun doing these. I learned the actual operation of Contains() formula which was giving me for no reason a lot of trouble. I also find it interesting so the different ways this can be completed. I do think though that when it says since June 2013 it should be clarified to say since July 1, 2013. I read it as June 1, 2013 and ended up with a different answer. I didint want to open the full solution workflow and ended up spinning my wheels for too long to try and resolve what was not a flow issue but a clarificaiton issue.
In the future I think the terminology should be as specific as possible since we arent in a client meeting with the ability to get explicit answers in situations like these