You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[4-[2-(6-bromo-3-ethyl-4-oxoquinazolin-2-yl)sulfanylacetyl]phenyl]acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H18BrN3O3S
assistant