You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(E)-but-2-enedioic acid;(2E)-2-ethylidene-1-(5-fluoro-1-benzofuran-7-yl)piperazine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H19FN2O5
assistant