You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-[2-(3,5-difluoro-4-methylphenyl)ethynyl]-1,3-dimethyl-2-[2-(4-methylphenyl)ethynyl]benzene is the IUPAC name of a molecule. Please give its molecular formula.
user
C26H20F2
assistant