You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl 3-[(3S)-7-bromo-2-[2-(2-methoxyacetyl)hydrazinyl]-5-pyridin-2-yl-3H-1,4-benzodiazepin-3-yl]propanoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22BrN5O4
assistant