c1cncnc1
c1ccc2ncncc2c1
c1ccc(cc1)c2ccccn2
c1cnc(nc1)n2cccn2
c1ncc2nc[nH]c2n1
c1ccc(cc1)n2ncc3c2ncnc3
O=C1c2ccccc2C(=O)c3c1cccc3