You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[[6-bromo-3-(4-ethoxycarbonylphenyl)-4-oxoquinazolin-2-yl]methylsulfanyl]acetic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H17BrN2O5S
assistant