You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-methyl-2-(1-methyl-4,5,6,7-tetrahydroindazole-3-carbonyl)-1,3,4,6,7,7a-hexahydropyrrolo[3,4-c]pyridine-3a-carboxylic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H26N4O3
assistant