O=C(Nc1ccc(Cl)cc1Cl)C1C(=O)N(c2ccc(Cl)cc2Cl)C(=O)/C1=N\Nc1ccc([N+](=O)[O-])cc1[N+](=O)[O-]
Heavy atom refers to any atom that is not hydrogen. The heavy atoms in molecules are carbon, oxygen, nitrogen, and sulfur. How many heavy atoms are in the molecule?