You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
tert-butyl (1R,2R,4S)-2-(5-bromo-6-oxo-1H-pyridin-3-yl)-7-azabicyclo[2.2.1]heptane-7-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H21BrN2O3
assistant