You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 3-[3-[(Z)-[3-[4-(carboxymethyl)phenyl]-4-oxo-2-sulfanylidene-1,3-thiazolidin-5-ylidene]methyl]phenoxy]propanoic acid into its molecular formula.
user
C21H17NO6S2
assistant