can anybody tell me what happens if i book a "Second night free" hotel...

that is i need two night, and the rate i get is 138$ for first night and second one is 0... how many rewardnights will i get ??

this half rate is about the same if i book 4 nights (there is some special 10% discount, which is actually lower rate than 2 paid night and 2 free nights under this promo...)