You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-N-[(3aS,6aR)-3-(4-fluorophenyl)-5,5-dioxo-3a,4,6,6a-tetrahydrothieno[3,4-d][1,3]thiazol-2-ylidene]-2-phenoxypropanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H19FN2O4S2
assistant