pls help

Let $$p(x,y) = \begin{cases} x + y &\quad \text{if } x \ge 0 \text{ and } y \ge 0, \\ x - 2y &\quad \text{if } x < 0 \text{ and } y < 0, \\ 3x + y &\quad \text{otherwise}. \end{cases}$$ What is $p(p(1,-1),p(-5,-2))$?