You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (8R,9S,13S,14S)-13-methyl-3-(6-methyl-1,2,4,5-tetrazin-3-yl)-7,8,9,11,12,14,15,16-octahydro-6H-cyclopenta[a]phenanthren-17-one into its molecular formula.
user
C21H24N4O
assistant