You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(3-methoxypropyl)-1-[1-(3-methyl-1,2,4-oxadiazol-5-yl)ethylsulfanyl]-[1,2,4]triazolo[4,3-a]quinazolin-5-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H20N6O3S
assistant