You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by (3S,13R,16S,17R,19S)-3-amino-18,18-dimethyl-13-(2-oxohex-5-enoyl)-1-azatricyclo[14.4.0.017,19]icosane-2,15-dione ?
user
C27H42N2O4
assistant