Question 22
Let $S_1$ and $S_2$ be sets of points on the coordinate plane $\mathbb R^2$ defined as follows: $$S_1=\{(x,y)\in\mathbb R^2:|x+|x||+|y+|y||\le2\},$$ $$S_2=\{(x,y)\in\mathbb R^2:|x-|x||+|y-|y||\le2\}.$$ Find the area of the intersection of $S_1$ and $S_2$.