O=C(O)c1ccc(N2C(=O)c3ccc(C(=O)c4cccc([N+](=O)[O-])c4)cc3C2=O)cc1
A rotatable bond is defined as any single non-ring bond, attached to a non-terminal, non-hydrogen atom. Amide C-N bonds are not counted because of their high barrier to rotation.  How many rotatable bonds does the molecule have?