Find the value of $\; \tan^{-1}\bigg(\tan{\frac{5\pi}{6}}\bigg)+\cos^{-1}\bigg(\cos{\frac{13\pi}{6}}\bigg)$

Question

$\begin{array}{1 1} 0 \\ 3 \pi \\ \pi \\ \frac{\pi}{3} \end{array} $