You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3,5,12,14-tetraoxatricyclo[14.2.2.27,10]docosa-1(19),7,9,16(20),17,21-hexaene-4,13-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H16O6
assistant