You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule N-[(2S,3R)-1-(3,5-difluorophenyl)-3-hydroxy-4-[[2-(methylsulfonylmethyl)phenyl]methylamino]butan-2-yl]acetamide ?
user
C21H26F2N2O4S
assistant