Three Dimensional Geometry

The equation of the perpendicular drawn from the point $A(6,1,3)$ to the line $\frac{x-1}{2}=\frac{2-y}{-1}=\frac{z-3}{2}$ is $\frac{x-6}{\boldsymbol{a}}=\frac{y-1}{\boldsymbol{b}}=\frac{z-3}{\boldsymbol{c}}$. If $\mathbf{a}, \mathbf{b}, \mathbf{c}$ are the possible integers such that $\boldsymbol{a}<0$, then the value of $\boldsymbol{a}-\boldsymbol{b}+\mathbf{5} \boldsymbol{c}$ is: