You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(7-but-3-enyl-2-methyl-8,9-dihydro-5H-benzo[7]annulen-5-yl)-1-[4-(1H-imidazol-5-yl)butyl]piperidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C28H39N3
assistant