You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3aR,7aR)-2-(2-methyl-5-pyrazol-1-ylphenyl)sulfonyl-1,3,4,6,7,7a-hexahydropyrano[3,4-c]pyrrole-3a-carboxylic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H21N3O5S
assistant