season 21 semifinals are here and it's time for fans to vote!Following the Top 8 performances on Monday night, Tuesday's live show will feature the announcement of the Top 5 -- the performers who earned the most votes this week, as well as the winner of yet another Instant Save, a five-minute, fan-voted competition between the remaining performers for a chance to make it to next week's finals.During Tuesday's show, when host Carson Daly makes the announcement that Instant Save voting is open,