You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[4-(5-methyl-1,3,4-oxadiazol-2-yl)phenyl]-3-[[3-(2-methylpropyl)imidazol-4-yl]methyl]urea is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22N6O2
assistant