You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule [2-[methyl(thiophen-3-ylmethyl)amino]-2-oxoethyl] 4-(4-methylpiperidin-1-yl)-3-nitrobenzoate into molecular formula.
user
C21H25N3O5S
assistant