You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 6-[(2S)-2-chloropropanoyl]-2-[(2-methoxyphenyl)methyl]-3,5,7,8-tetrahydropyrido[4,3-d]pyrimidin-4-one into molecular formula.
user
C18H20ClN3O3
assistant