Let S be the set of all values of $\lambda$, for which the shortest distance between the lines $\frac{x-\lambda}{0}=\frac{y-3}{4}=\frac{x+6}{1}$ and $\frac{x+\lambda}{3}=\frac{y}{-4}=\frac{x-6}{0}$ is 13 . Then $8\left|\sum_{x \in \text { S }} \lambda\right|$ is equal to
