Let A = [a, b; c, d] and B = [α; β] ≠ [0; 0] such that AB = B and a + d =2021, then the value of ad - bc is equal to \ \ \ \.

Let $\displaystyle \mathrm{A}=\left[\begin{array}{ll}\mathrm{a} & \mathrm{b} \\ \mathrm{c} & \mathrm{d}\end{array}\right]$ and $\displaystyle \mathrm{B}=\left[\begin{array}{l}\alpha \\ \beta\end{array}\right] \neq\left[\begin{array}{l}0 \\ 0\end{array}\right]$ such that $\displaystyle \mathrm{AB}=\mathrm{B}$ and $\displaystyle \mathrm{a}+\mathrm{d}=2021$, then the value of $\displaystyle \mathrm{ad}-\mathrm{bc}$ is equal to \_\_\_\_.