You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-[1-(5-chloro-2-methoxyphenyl)pyrrolidin-3-yl]-4-oxo-2-sulfanylidene-1H-quinazoline-7-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C20H19ClN4O3S
assistant