You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (2R,3R)-2-(2,4-difluorophenyl)-3-[(4-fluorophenyl)methyl-methylamino]-1-(1,2,4-triazol-1-yl)butan-2-ol into its molecular formula.
user
C20H21F3N4O
assistant