You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (2R,3S,4R,5R,6S)-2-[[(1S,4aS,7aR)-4a-hydroxy-7-(hydroxymethyl)-5,7a-dihydro-1H-cyclopenta[c]pyran-1-yl]oxy]-6-(hydroxymethyl)oxane-3,4,5-triol into molecular formula.
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C15H22O9
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