You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 4-bromo-N-[(Z)-[2,5-dimethyl-1-(2-methyl-5-nitrophenyl)pyrrol-3-yl]methylideneamino]benzamide is given. What is its corresponding molecular formula?
user
C21H19BrN4O3
assistant