You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1,3,6,7-tetrahydroxy-2-[(E)-3-methoxybut-2-enyl]-8-(3-methylbut-2-enyl)xanthen-9-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H24O7
assistant