You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1R)-1-(5-chloropyridin-2-yl)-1-[3-fluoro-5-(trifluoromethyl)phenyl]-2-phenylethanamine is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H15ClF4N2
assistant