You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[(5Z)-5-[[1-[(2-fluorophenyl)methyl]benzimidazol-2-yl]methylidene]-4-oxo-2-sulfanylidene-1,3-thiazolidin-3-yl]propanoic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H16FN3O3S2
assistant