Numerical analysis — value of an interpolating polynomial

If $p(x)$ is the interpolating polynomial for the data

$$\begin{array}{c|ccccc} x & -2 & -1 & 0 & 1 & 2\\ y & -1 & 3 & 1 & -1 & 3 \end{array}$$

then the value of $p\left(\dfrac12\right)$ is