You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 3,9-dimethyl-1-(3-methylbutyl)-7-(2-methylprop-2-enyl)-4H-purino[8,7-c][1,2,4]triazine-6,8-dione ?
user
C18H26N6O2
assistant