You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-chloro-N-[(3-fluoro-4-methoxyphenyl)methyl]-N-[(2R)-1-hydroxy-4-methylpentan-2-yl]benzenesulfonamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H25ClFNO4S
assistant