You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named N-(2,4-difluorophenyl)-2-[[5-(4-ethoxyphenyl)-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-6-yl]sulfanyl]acetamide is given. What is its corresponding molecular formula?
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C21H17F2N5O3S
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