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 8-bromo-N-[(5,6-difluoro-1H-benzimidazol-2-yl)methyl]-2-(4-methylpiperazin-1-yl)pyrazolo[1,5-a][1,3,5]triazin-4-amine .
user
C18H18BrF2N9
assistant