You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named ethyl 2-[(2S)-2-benzyl-3,5-dioxo-1,4-diazaspiro[5.5]undecan-4-yl]acetate is given. What is its corresponding molecular formula?
user
C20H26N2O4
assistant