You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 4-(2-ethyl-5-methyl-1H-imidazol-4-yl)-1-methyl-3-pyridin-2-yl-5,7-dihydro-4H-pyrazolo[3,4-b]pyridin-6-one .
user
C18H20N6O
assistant