Probability mass function

You were given a discrete random variables $X$ with values $x\in\{1,2,3\}$ and $Y$ with values $y\in \{1, -2, -3\}$.

Let's say a discrete random variable $Z = X + Y$.

Calculate the value for $p_Z(0)$.

Tip:

Formula for the PMF is this:

$p_Z(z) = P(Z=z) = P(\{\omega \in \Omega \hspace{0.2cm} such \hspace{0.1cm} that \hspace{0.2cm} Z(\omega)=z\})$

Round the result to two decimal places.