You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(4-chloro-2-fluorophenyl)-2-[(4-oxo-1-phenyl-5H-pyrazolo[3,4-d]pyrimidin-6-yl)sulfanyl]propanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H15ClFN5O2S
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