You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-methyl-4-(2-methylphenyl)spiro[7-thia-1,4,9-triazatricyclo[6.3.0.02,6]undeca-2(6),8,10-triene-3,1'-cyclopentane] is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H21N3S
assistant