You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[6-(3-bromopyridin-2-yl)-3,4a,5,7,8,8a-hexahydro-2H-pyrido[4,3-b][1,4]oxazin-4-yl]ethanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C14H18BrN3O2
assistant