Determinant of order 4

Compute the determinant

\begin{vmatrix} 2 & 1 & 0 & 3 \\ 0 & 1 & 0 & 0 \\ 1 & 3 & 2 & 1 \\ 0 & 2 & 0 & 1 \end{vmatrix} .

The full solution of this exercise is in the unlocked version.