You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (4R,5R,7R)-5-[(1S,2R,3R)-3-[(E,2R,5R)-5,6-dimethylhept-3-en-2-yl]-2-(2-hydroxyethyl)-2-methylcyclopentyl]-8-hydroxy-7-methyl-9-oxatricyclo[5.2.2.04,8]undecane-3,6-dione by IUPAC nomenclature, provide its molecular formula.
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C28H44O5
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