You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-N-[2-(N-methylanilino)ethyl]-2-(2-methyl-N-methylsulfonyl-5-nitroanilino)propanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H26N4O5S
assistant