You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-[(3R,4R)-4-tert-butyl-3-hydroxypiperidine-1-carbonyl]-3-ethyl-1H-quinazoline-2,4-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H27N3O4
assistant