You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named methyl 2-[4-(2-chloro-4-hydroxyphenyl)-4-hydroxypiperidin-1-yl]pyridine-4-carboxylate is given. What is its corresponding molecular formula?
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C18H19ClN2O4
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