You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule [(4S,8S,9S,9bS)-8-hydroxy-3,6-dimethylidene-2-oxospiro[3a,4,5,6a,7,8,9a,9b-octahydroazuleno[4,5-b]furan-9,2'-oxirane]-4-yl] 2-methyloxirane-2-carboxylate into molecular formula.
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C19H22O7
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