Students-Far From Hostel

It's late at night, and the college students are required to return to their college hostels from the hostel garden. The hostel garden is a rectangular field of dimensions $N \times M$, with two hostels — one across the left edge and one across the top edge of the field. Students are currently in the cells of the field. You are given two matrices of size $N \times M$, $A$ and $B$. $A_{i, j}$ den