You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(1-cyano-1-cyclopropylethyl)-2-[3-methyl-4-[(1-methylimidazol-2-yl)methyl]piperazin-1-yl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H28N6O
assistant