You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule [2-[(15Z,18Z)-hexacosa-15,18-dienoyl]oxy-3-[(Z)-icos-11-enoyl]oxypropyl] (17Z,20Z)-octacosa-17,20-dienoate into molecular formula.
user
C77H140O6
assistant