You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule N-(2-hydroxyethyl)-N,4-dimethyl-3-(6-methyl-[1,2,4]triazolo[3,4-a]phthalazin-3-yl)benzenesulfonamide into molecular formula.
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C20H21N5O3S
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