You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3S,4R,4aR,6S)-6-tert-butyl-2-imino-4-thiophen-3-yl-3,4,4a,5,6,7-hexahydronaphthalene-1,1,3-tricarbonitrile by IUPAC nomenclature, provide its molecular formula.
user
C21H22N4S
assistant