You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R,3R)-2-ethyl-8,10-dihydroxy-3-(4-hydroxy-3,5-dimethoxyphenyl)-2,3-dihydro-[1,4]dioxino[2,3-c]xanthen-7-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C25H22O9
assistant