['CCc1nncn1C', 'O=C1CNCN1CC(F)(F)F', 'CC(F)(F)F', 'CC(c1nncn1C)N1CNC(=O)C1', 'Cn1cnnc1', 'CCN1CC(=O)N(CC(F)(F)F)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1CN(Cc2nnc[nH]2)CN1.