You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 3-N-methyl-5-[2-(1-methyl-2H-pyridin-2-yl)-1,2-dihydropyridin-5-yl]benzene-1,3-diamine into molecular formula.
user
C18H22N4
assistant