You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-[[(2S)-1-[(2S)-2-[[(2S)-2-aminopropanoyl]amino]-3-methylbutanoyl]pyrrolidin-2-yl]methyl]-N-(2-phenylethyl)benzamide by IUPAC nomenclature, provide its molecular formula.
user
C28H38N4O3
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