You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (1S,3R,3aR,6aS)-5-butyl-1-(2-hydroxyphenyl)-3-(2-methylpropyl)-4,6-dioxo-1,2,3a,6a-tetrahydropyrrolo[3,4-c]pyrrole-3-carboxylic acid into its molecular formula.
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C21H28N2O5
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