Hello, I'm having a little trouble with this problem:

Raul works for Norwalk Parking Authority and is studying the parking rates for short term parking (up to 24 hours) in a new parking garage. Payment is in half hour increments and a customer cannot pay for part of an increment. The first half hour is free (up to and including 30 minutes). The second half hour is $2.00 (any amount of time over 30 minutes, up to and including 60 minutes). Each additional half hour is $1.00. The maximum daily rate is $24.00. Create a piecewise function which represents this fee structure.

I know the first two [expressions] are "0" if 0 < x< 30, and "2" if 30 < x <60, but I need help figuring out the last one