O=C(Nc1nnc(-c2c(Cl)c(Cl)c(Cl)c(Cl)c2-c2nc3cc(C(=O)c4ccccc4)ccc3[nH]2)o1)c1ccc(Cl)cc1
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?