You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R,3R,3aS,9bS)-1-(cyclopropylmethyl)-N-[(2-fluorophenyl)methyl]-3-(hydroxymethyl)-6-oxo-3,3a,4,9b-tetrahydro-2H-pyrrolo[2,3-a]indolizine-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H26FN3O3
assistant