You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (6S)-3-(2-methoxyethyl)-4-methyl-2-oxo-6-(2-phenylethyl)-1,6-dihydropyrimidine-5-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H24N2O4
assistant