You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name 9-chloro-7-(4-ethyl-5-fluoropyridin-3-yl)-8-fluoro-1-methyl-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline ?
user
C18H15ClF2N4
assistant