You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
9-[4-[2-(dimethylamino)ethyl]-3-fluorophenyl]-8-hydroxy-5H-thieno[2,3-c]quinolin-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H19FN2O2S
assistant