['CCO', 'O=CNNS(=O)(=O)c1ccc(F)c(C(F)(F)F)c1', 'CC', 'O=C(O)NNS(=O)(=O)c1ccc(F)c(C(F)(F)F)c1', 'FC(F)F', 'CCOC(=O)NNS(=O)(=O)c1ccc(F)cc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.