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 N-(5-chloro-2-methoxyphenyl)-2-[2-(2-fluorophenyl)ethylamino]pyridine-4-carboxamide is given. What is its corresponding molecular formula?
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C21H19ClFN3O2
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