You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2E)-2-cyano-2-[(5E)-5-[(3-methoxyphenyl)methylidene]-4-oxo-3-phenyl-1,3-thiazolidin-2-ylidene]-N-methylacetamide by IUPAC nomenclature, provide its molecular formula.
user
C21H17N3O3S
assistant