You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-[[6-amino-5-[2-(3,5-difluoropyridin-2-yl)ethynyl]pyrimidin-4-yl]amino]ethyl]-5-chloro-3-phenylquinazolin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C27H18ClF2N7O
assistant