You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule 4-[(3E,5Z)-5-ethylidene-4,8,8,8-tetrafluoro-6-methylocta-1,3-dien-2-yl]-2-methyl-2,3,4a,5,6,7,8,8a-octahydro-1H-quinoxaline ?
user
C20H30F4N2
assistant