O=C(NCCN(CCNC(=O)c1nc[nH]c1C(=O)Nc1cccc(Cl)c1)CCNC(=O)c1nc[nH]c1C(=O)Nc1cccc(Cl)c1)c1nc[nH]c1C(=O)Nc1cccc(Cl)c1
How many heavy atoms like carbon, oxygen, nitrogen, sulfur and other non-hydrogen atoms do the molecule contain?