O=C(c1ccccc1)c1nc2ccccc2n(CCCn2c(=O)c(C(=O)c3ccccc3)nc3ccccc32)c1=O
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?