You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[3-[4-[(5-chlorothiophen-2-yl)methyl]piperazin-1-yl]-3-oxoprop-1-enyl]benzonitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H18ClN3OS
assistant