You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 5,7-dihydroxy-2-(4-hydroxyphenyl)-3-[(2S,3S,5R)-3,4,5-trihydroxy-6-methyloxan-2-yl]oxychromen-4-one into molecular formula.
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C21H20O10
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