You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(2,6-diethyl-4-methylphenyl)-7-hydroxy-7-methyl-5,6,8,9-tetrahydropyrazolo[1,2-a]diazepine-1,3-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28N2O3
assistant