You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(5Z)-5-[(3,4-dihydroxyphenyl)methylidene]-4-oxo-2-sulfanylidene-1,3-thiazolidin-3-yl]-2-phenylacetic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H13NO5S2
assistant