You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(3-aminopiperidine-1-carbonyl)-7a-methyl-2,3,6,7-tetrahydropyrrolo[2,1-b][1,3]thiazol-5-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H21N3O2S
assistant