Let $$A = \left[ {\matrix{ a & b \cr c & d \cr } } \right]$ and $B = \left[ {\matrix{ \alpha \cr \beta \cr } } \right] \ne \left[ {\matrix{ 0 \cr 0 \cr } } \right]$ such that AB = B and a + d = 2021, then the value of ad $-$$ bc is equal to ___________.