You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-(3,5-difluorophenyl)-N-(1-hydroxypropan-2-yl)-6-(4-methylphenyl)-3-oxopyridazine-4-carboxamide by IUPAC nomenclature, provide its molecular formula.
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C21H19F2N3O3
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