['NC(N)=O', 'CC(C=O)Sc1ncccc1[N+](=O)[O-]', 'NC=O', 'CC(Sc1ncccc1[N+](=O)[O-])C(N)=O', 'CCC(=O)NC(N)=O', 'O=[N+]([O-])c1cccnc1S', 'CC(S)C(=O)NC(N)=O', 'O=[N+]([O-])c1cccnc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccncc1.