['CNC(N)=S', 'Cc1ccccc1-n1ccnc1', 'CNC(=S)NC', 'c1ccc(-n2ccnc2)cc1', 'c1c[nH]cn1', 'CNC(=S)NCc1ccccc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-n2ccnc2)cc1.