You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name 1-[[6-chloro-5-(hydroxymethyl)pyridin-3-yl]methyl]-4-(4-cyanophenyl)-2,5-dimethylpyrrole-3-carbonitrile into its molecular formula.
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C21H17ClN4O
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