You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 1-[(3-chlorophenyl)methyl]-1,2-dimethyl-3-[4-(2-methylimidazol-1-yl)butyl]guanidine;hydroiodide into its molecular formula.
user
C18H27ClIN5
assistant