You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[2-[1-(3,4-dimethylphenyl)ethylamino]-2-oxoethyl]-5-methylpiperidine-3-carboxylic acid by IUPAC nomenclature, provide its molecular formula.
user
C19H28N2O3
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