You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 1-[(2S,4R)-7-chloro-2-(difluoromethyl)-2-methyl-3,4-dihydrochromen-4-yl]-3-(1-methyl-2-oxo-3,4-dihydroquinazolin-5-yl)urea ?
user
C21H21ClF2N4O3
assistant