I have a joint pdf function

$$
f\_{X,Y}(x,y) = \begin{cases} A, & \mbox{ } 0\le|x|+|y|<1\mbox{} \\ 0, & \mbox{otherwise } \mbox{ } \end{cases}
$$

I want to find value of A by using this formula: $$\int\_{x}\int\_{y}f\_{X,Y}(x,y)dxdy=1$$ which becomes after subsituting value: $$\int\_{x}\int\_{y}(A)dxdy=1$$ My question is how the values of 'x' and 'y' intervals are calculated from given information.