Task B-4.7. Vectors $\vec{a}=2 \vec{m}+\vec{n}$ and $\vec{b}=\vec{m}-\vec{n}$ determine a parallelogram. Here, $\vec{m}$ and $\vec{n}$ are unit vectors, and the measure of the angle between $\vec{m}$ and $\vec{n}$ is $\frac{\pi}{3}$. Determine the area of the parallelogram determined by vectors $\vec{a}$ and $\vec{b}$.