Tom and Jerry

Tom and Jerry have $B$ boxes, numbered from $1$ to $B$. Each box initially contains $M$ cheese balls and $N$ chicken bones. They perform the following process for each $i$ from $1$ to $B-1$, **in order**: - Choose $i$ random items from the $i$-th box, and transfer them to box $(i+1)$. Every subset of $i$ items is equally likely to be chosen. You are given integers $B, M, N, $ and $K$. At the