You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-3-amino-2-[2,2-dimethylpropyl(ethyl)amino]-N-[2-fluoro-4-(3-oxomorpholin-4-yl)phenyl]propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H31FN4O3
assistant