You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-N-[(2S)-butan-2-yl]-1-cyclopentyl-4-oxo-5-N-(thiophen-2-ylmethyl)pyridine-3,5-dicarboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H27N3O3S
assistant