You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (E)-6-(4-hydroxy-6-methoxy-7-methyl-3-oxo-1H-2-benzothiophen-5-yl)-4-methylhex-4-enoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22O5S
assistant