You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5Z)-5-[[2-(2,4-dichlorophenoxy)-9-methyl-4-oxopyrido[1,2-a]pyrimidin-3-yl]methylidene]-3-methyl-2-sulfanylidene-1,3-thiazolidin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H13Cl2N3O3S2
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