You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named acetic acid;(5Z)-3-(2-methylpropyl)-5-[(E)-3-phenylprop-2-enylidene]-2-sulfanylidene-1,3-thiazolidin-4-one by IUPAC nomenclature, provide its molecular formula.
user
C18H21NO3S2
assistant