You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule N-[4-(3-aminopropanoylamino)cyclohexyl]-7-bromo-2,3,3a,4,5,6,7,7a-octahydro-1H-indole-2-carboxamide .
user
C18H31BrN4O2
assistant