Reason: Dye 24 points red and blue respectively, as shown below.

Red, blue, red, empty red

Blue, red, blue, red, blue

Red blue red blue red.

Blue, red, blue, red, blue

Red blue red blue red.

There are 13 red dots and 1 1 blue dots on the graph.

According to the rules, red dots can only be connected to blue dots, and blue dots can only be connected to red dots.

So a line connecting 24 points must be 12 red dot and 12 blue dot, but it can't be 13 red dot and10/blue dot.