You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[2-[[7-[[dimethyl(oxo)-lambda6-sulfanylidene]amino]-5-methylquinazolin-4-yl]amino]-5-fluorophenoxy]-N-ethylacetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H24FN5O3S
assistant