Let A ={(x, y) ∈ R × R:|x+y| ≥ 3} and B ={(x, y) ∈ R × R:|x|+|y| ≤ 3}. If C ={(x, y) ∈ A ∩ B: x=0 or y=0}, then Σ_(x, y) ∈ C |x+y| is:

Let $\displaystyle \mathrm{A}=\{(x, y) \in \mathbf{R} \times \mathbf{R}:|x+y| \geqslant 3\}$ and $\displaystyle \mathrm{B}=\{(x, y) \in \mathbf{R} \times \mathbf{R}:|x|+|y| \leq 3\}$. If $\displaystyle \mathrm{C}=\{(x, y) \in \mathrm{A} \cap \mathrm{B}: x=0$ or $\displaystyle y=0\}$, then $\displaystyle \sum_{(x, y) \in \mathrm{C}}|x+y|$ is :