A party is a group chat, the only difference being there's a "leader" (this is the person who started the chat)
In these parties, there can only be 5 maximum users, this includes the leader.
In addition to that, you may only be the leader of a single party at any given moment in time. You can be a member of as many parties which invite you.
Now, if there were $n$ users on this site, and they equally spread out into as many parties as they could (e.g. Every user was in 5 parties), how many parties would coexist on the site at that moment?