What is the optimal way to cut B chocolate bars to share equally between N people?

Here is an example of different cuts for B = 5 chocolate bars and N = 6 people.

Strategy 1: cut each chocolate bar in 6 equal parts and, then, give 5 parts for each person. Number of cuts: 5 x 5 = 25.

Strategy 2: cut 3 bars in 2 equal parts and cut 2 parts in 3 equal parts and, then, give 1/2 bar and 1/3 bar for each person. Number of cuts: 3 x 1 + 2 x 2 = 7.

What is the optimal solution for the general problem?

Thanks, Humberto.