You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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1-ethyl-N-(4-fluoro-2-methylphenyl)-2,4-dioxo-7-propan-2-ylpyrido[2,3-d]pyrimidine-5-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
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C20H21FN4O3
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