You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance ethyl 2-[1-hydroxy-2-[6-oxo-3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl)pyridazin-1-yl]cyclohexyl]acetate .
user
C27H28N4O4
assistant