Find the value of `p` such that $ \begin{bmatrix} 1 & p & 1 \end{bmatrix} \times \begin{bmatrix} 1 & 3 & 2 \\ 2 & 5 & 1 \\ 15 & 3 & 2 \end{bmatrix} \times \begin{bmatrix} 1 \\ 2 \\ p \end{bmatrix} = 0 $