You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (2R)-2-(2,6-dichlorophenyl)-2-[6-(2,4-difluorophenyl)sulfanylpyridazin-3-yl]acetamide by IUPAC nomenclature, provide its molecular formula.
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C18H11Cl2F2N3OS
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