You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[(1-ethylcyclobutyl)methyl]-3-[(2-imidazol-1-ylpyridin-4-yl)methyl]-2-methylguanidine by IUPAC nomenclature, provide its molecular formula.
user
C18H26N6
assistant