You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-[4-(5-chloropyridin-2-yl)sulfanyl-3-[4-(methylsulfonylmethyl)phenyl]pyrazol-1-yl]pyrimidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H16ClN5O2S2
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