You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (2S)-2-[6-(4-fluorophenyl)thieno[3,2-d]pyrimidin-4-yl]sulfanyl-N-[[(2R)-oxolan-2-yl]methyl]propanamide into its molecular formula.
user
C20H20FN3O2S2
assistant