You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-(2,3-dihydroindol-1-yl)-2-oxoethyl] 2-(2,4-dioxo-1,3-diazaspiro[4.4]nonan-3-yl)acetate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H21N3O5
assistant