You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule [2-(3,4-difluorophenyl)-2-oxoethyl] (2R)-2-[(2,4-dichlorobenzoyl)amino]-4-methylsulfanylbutanoate .
user
C20H17Cl2F2NO4S
assistant