You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5E)-2-(2,6-dimethylphenyl)imino-5-[(1-phenylpyrazol-4-yl)methylidene]-1,3-thiazolidin-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H18N4OS
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