You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[(4-fluorophenyl)methylsulfanyl]-1-[2-(pyrrolidin-1-ylmethyl)piperidin-1-yl]propan-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H29FN2OS
assistant