Complex Numbers

Let

$A = \{ z \in \mathbb{C} : |z - 2| \leq 4 \}$ and

$B = \{ z \in \mathbb{C} : |z - 2| + |z + 2| = 5 \}$.

Then the max $\{|z_1 - z_2| : z_1 \in A \text{ and } z_2 \in B \}$ is :