# Party acquaintances

There are $$n$$ people at a party. Suppose they are friendly people, and each person has 8 acquaintances. Now, Bob, a passer-by notices this special property:

(i) Each pair of people who are mutually acquainted has exactly 4 common acquaintances.

(ii) Each pair of people who are mutually unacquainted has exactly 2 common acquaintances

Find the number of possible values of $$n$$.