You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(8-ethyl-2,4-dioxo-1,3-diazaspiro[4.5]decan-3-yl)-N-[1-(3-sulfamoylphenyl)ethyl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28N4O5S
assistant