You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
spiro[1,3-dioxepine-2,6'-3,4,7,8,9,10-hexahydro-2H-pyrimido[1,2-a]azepine]-4,7-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H16N2O4
assistant