You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2Z)-2-[(5E)-4-oxo-3-prop-2-enyl-5-(pyridin-2-ylmethylidene)-1,3-thiazolidin-2-ylidene]-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acetonitrile by IUPAC nomenclature, provide its molecular formula.
user
C21H20N6OS
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