['CCCCO', 'Cc1cc(N)n2nc(C(F)(F)F)nc2n1', 'CC[C@@H](N)CO', 'Cc1ccn2nc(C(F)(F)F)nc2n1', 'FC(F)F', 'CC[C@H](CO)Nc1cc(C)nc2ncnn12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnc2ncnn2c1.