You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-bromo-1-[(5-ethyl-1,3,4-oxadiazol-2-yl)methyl]-6-methyl-2-oxopyridine-3-carbonitrile The above is the IUPAC name of a molecule. Write its molecular formula.
user
C12H11BrN4O2
assistant