You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 2-methyl-5-[5-methyl-4-(2-methylpropyl)thiophen-2-yl]-3-(2-methylpropyl)thiophene is given. What is its corresponding molecular formula?
user
C18H26S2
assistant