You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-(5-chloro-2-hydroxyphenyl)-4-[4-(dimethylamino)phenyl]-5,6-dihydro-1H-pyrimidine-2-thione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H18ClN3OS
assistant