Figure 2:

Example with B_i = {45, 60}. (a) Point 45 (circled), points 1 through 45 (black or red), J₄₅ (red). (b) Point 60 (circled), points 1 through 60 (black or blue), J₆₀ (blue). (c) Points 1 through 60 (not gray), ${\overline{J}}_{45}$ (purple), ${\overline{J}}_{60}$ (purple + blue). ${\overline{J}}_{45}$ has three more points than J₄₅, and ${\overline{J}}_{60}$ has 7 more points than J₆₀.