You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 4-methoxy-N-[2-[methyl-[2-(4-methylanilino)-2-oxoethyl]amino]-2-oxoethyl]-3-nitrobenzamide by IUPAC nomenclature, provide its molecular formula.
user
C20H22N4O6
assistant