You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-[(3,4-dimethoxyphenyl)methyl]-5,7-dimethylpyrido[2,3-d]pyrimidine-2,4-diamine;hydrochloride is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22ClN5O2
assistant