You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[3-oxo-3-(4-propyl-2,3-dihydro-1,4-benzoxazin-7-yl)propyl]piperidine-4-carboxylic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H28N2O4
assistant