You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[2-(5-methyl-[1,2,4]triazolo[1,5-a]pyridin-2-yl)ethyl]-5,6-dihydro-[1,2,4]triazolo[5,1-f][1,6]naphthyridine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H17N7
assistant