You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-[1-(3-methylazetidin-1-yl)ethyl]-2-phenyl-1,6-dihydro-1,3,6-triazonin-7-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22N4O
assistant