Rank all your specialties, then rank all your prelims on your primary. Then, under each specialty program, create a supplemental list of prelim programs, so that if you match at that program, you will then be considered for the prelims on your supplemental list (because everything further down your primary rank list will then be ignored.)
If you do this, you'll know when you get your email whether you've fully matched or not.
If you don't match at any of your advanced programs, and fall to your prelim programs on the primary rank list, your email will say, " congratulations, you have matched to a one-year program."
If you match one of the advanced programs at the top, but not one of the prelim programs on your supplemental list, your email will say, "congratulations, you have matched to an advanced program, but not a preliminary program." or something to that effect.
If you match an advanced program and a prelim off your supplemental list for that program, or if you didn't enter a supplemental list for that program, your email will read, simply, " congratulations, you have matched."
This is all on the NRMP Information Pages on the website, by the way. So you could, you know, look it up yourself instead of relying on secondhand info from random strangers.