You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
tert-butyl (2S,3aS,8bR)-2,4-diformyl-8b-(2-methylbut-3-en-2-yl)-2,3a-dihydro-1H-pyrrolo[2,3-b]indole-3-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H28N2O4
assistant