['CCN', 'CN(CC(=O)NC=O)Cc1ccccc1[N+](=O)[O-]', 'CCNC=O', 'CN(CC(N)=O)Cc1ccccc1[N+](=O)[O-]', 'CCNC(N)=O', 'CN(CC=O)Cc1ccccc1[N+](=O)[O-]', 'CC', 'CN(CC(=O)NC(N)=O)Cc1ccccc1[N+](=O)[O-]', 'CCNC(=O)NC(C)=O', 'CNCc1ccccc1[N+](=O)[O-]', 'Cc1ccccc1[N+](=O)[O-]', 'CCNC(=O)NC(=O)CNC', 'O=[N+]([O-])c1ccccc1', 'CCNC(=O)NC(=O)CN(C)C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.