O=C1C2Cc3c([nH]c4ccccc34)C(c3ccccc3)N2C(=O)C2Cc3c([nH]c4ccccc34)C(c3ccccc3)N12
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?