['Cc1cn2ncsc2n1', 'O=[N+]([O-])c1ccccc1N1CCNCC1', 'O=[N+]([O-])c1ccccc1', 'Cc1cn2nc(N3CCNCC3)sc2n1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(N2CCN(c3nn4ccnc4s3)CC2)cc1.