Puzzle n°48 (*) - The Feline Judges Seminar

A seminar for feline judges was organised recently. More than 16 judges were registered, but less than 40. Unfortunately, several of them did not manage to come ; in fact, exactly 2 out of 7 registered persons did not. During the seminar, I noticed that there were as many men as women. How many persons took part in the seminar ?

... I'm giving up...