O=C(NCc1ccccc1)C1C(=O)N(Cc2ccccc2)C(=O)C1C1(O)CCCC1
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?