You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 5,8-dimethyl-2-(3-methyl-2-phenylimidazo[1,2-a]pyridin-7-yl)-[1,2,4]triazolo[1,5-a]pyrazine .
user
C21H18N6
assistant