You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 2-[(4-phenylpiperazin-1-yl)methyl]-3,4-dihydro-2H-[1,3]thiazino[3,2-a]benzimidazole is given. What is its corresponding molecular formula?
user
C21H24N4S
assistant