You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[[1-(4-chlorophenyl)-4-oxo-5H-pyrazolo[3,4-d]pyrimidin-6-yl]sulfanyl]-N-(4-methoxyphenyl)acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H16ClN5O3S
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