You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl 2-[(5Z)-5-[[2-[(4-bromophenyl)methoxy]phenyl]methylidene]-3-methyl-4-oxo-2-sulfanylideneimidazolidin-1-yl]acetate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H19BrN2O4S
assistant