Since you will be coming in as undeclared Letters and Sciences some of those seats are reserved for you. In particular, there are even more seats for undeclared letters and sciences incoming transfers. You can’t actually declare math or any other major in Letters and Sciences until you get here. Even though you are admitted for math, you are still considered as an undeclared Letters and Science incoming transfer student. Also, I’m a transfer student and I was admitted as a Pure Math student. I even declared math before I was interested in physics and cs. The lower division cs classes usually expand to take everyone on the waitlist (since it is webcasted), so even though I was declared math and don’t meet any of the requirements for the reserved seats, I was still able to get off the waitlist for the lower division CS classes the first week of school.