You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance (2Z)-3-[1-[(2Z)-2-(carboxymethylidene)pent-4-enoyl]oxy-1-oxohex-4-en-2-yl]oxycarbonylhexa-2,5-dienoic acid .
user
C20H22O9
assistant