You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(4-bromophenyl)methyl-[2-[(3,4-dichlorophenyl)methylsulfanyl]acetyl]amino]-N-butan-2-ylpropanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C23H27BrCl2N2O2S
assistant