Here's my attempt:

Suppose we have a set which is a subset of set of all wffs of the system-L, such that for all even n, and for all odd n. Then I guess we have to show it is consistent and complete.

is consistent if there is no wff A such that and .

is complete if for every we have either or .

I appreciate any help to get me started on this. I'm not sure how to start proving the two conditions...