If $$\overrightarrow{a}$$ and $$\overrightarrow{b}$$ are vectors in space given by $$\overrightarrow{a} = \frac{\hat{i} - 2 \hat{j}}{\sqrt{5}}$$ and $$\overrightarrow{b} = \frac{2\hat{i} + \hat{j} + 3\hat{k}}{\sqrt{14}}$$, then the value of $$\left(2\overrightarrow{a} + \overrightarrow{b}\right).\left[\left(\overrightarrow{a} \times \overrightarrow{b}\right) \times \left(\overrightarrow{a} - 2\overrightarrow{b}\right)\right]$$ is