You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
9-oxo-N-(5,6,7,8-tetrahydro-4H-cyclohepta[d][1,3]thiazol-2-yl)fluorene-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H18N2O2S
assistant