You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name (E)-2-cyano-3-(3,5-dichloropyridin-4-yl)-N-methyl-N-[(5E)-5-[(Z)-prop-1-enyl]octa-5,7-dien-4-yl]prop-2-enamide ?
user
C21H23Cl2N3O
assistant