You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1E,4E)-1-(3,4-dimethoxycyclohexa-1,5-dien-1-yl)-5-(3,4-dimethoxyphenyl)penta-1,4-dien-3-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H24O5
assistant