You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (4R)-4-[[(2-amino-5-ethyl-6-methylpyrimidin-4-yl)amino]methyl]-1-methyl-3,4-dihydroquinolin-2-one into molecular formula.
user
C18H23N5O
assistant