You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(5S)-5-[2-[(1S)-3-acetyl-4-methyl-1-nitrocyclohex-3-en-1-yl]ethyl]-2-methyl-5-nitrocyclohexen-1-yl]ethanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28N2O6
assistant