You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 5-[(E)-2-[(7R,10aR)-7-hydroxy-4-methoxy-8,8,10a-trimethyl-6,7,8a,9-tetrahydro-5H-xanthen-2-yl]ethenyl]-2-[(E)-2-(4-nitrophenyl)ethenyl]benzene-1,3-diol .
user
C33H35NO7
assistant