A $4 \times 4$ DFT matrix is given by

$\dfrac{1}{2} \begin{bmatrix} 1 & 1 & 1 & 1 \\ 1 & x & -1 & y \\ 1 & -1 & 1 & -1 \\ 1 & -j & -1 & j \end{bmatrix} \\ j^2 = -1$

Where the values of $x$ and $y$ are ______, _____ respectively.

- $1, -1$
- $-1,1$
- $-j,j$
- $j, -j$