You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 3-[7-[[[(2S,4S)-2-(aminomethyl)oxan-4-yl]amino]methyl]-3-oxo-1H-isoindol-2-yl]piperidine-2,6-dione into molecular formula.
user
C20H26N4O4
assistant