You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name ethyl (5S)-7-acetyl-8-methyl-4-(4-nitrophenyl)-9-phenyl-1,6-dithia-3,4,9-triazaspiro[4.4]nona-2,7-diene-2-carboxylate ?
user
C22H20N4O5S2
assistant