You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 6-[3,4-dihydroxy-6-methyl-5-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxan-2-yl]-5-hydroxy-2-(4-hydroxyphenyl)-7-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxychromen-4-one by IUPAC nomenclature, provide its molecular formula.
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C33H40O19
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