You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5-bromofuran-2-yl)-[7-methyl-6-(5-phenyl-1,3,4-oxadiazol-2-yl)-2,7-diazaspiro[3.4]octan-2-yl]methanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H19BrN4O3
assistant