You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(4-tert-butyl-1,3-thiazol-2-yl)methyl]-3-[2-(3-chlorophenyl)ethyl]-2-methylguanidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H25ClN4S
assistant