You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3S)-3-[[(2R)-3-acetamido-4-(3,5-difluorophenyl)-2-hydroxybutyl]amino]-3-(3-ethylphenyl)propanoic acid by IUPAC nomenclature, provide its molecular formula.
user
C23H28F2N2O4
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