You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3,3-dimethyl-N-[2-oxo-2-[(3R)-3-phenyl-5-thiophen-2-yl-3,4-dihydropyrazol-2-yl]ethyl]butanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H25N3O2S
assistant