You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4S)-3'-[2-oxo-2-(3-oxo-2,4-dihydroquinoxalin-1-yl)ethyl]spiro[2,3-dihydro-1H-naphthalene-4,5'-imidazolidine]-2',4'-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H20N4O4
assistant