There are N+1 points on the plane, number A,1,2…N. N is an odd integer. Initially, there exist (N+1)/2 edges, as shown in the picture below.
Now your mission is add some edges to the graph, makes that
① degree(i) != degree(j), (i != j, 1 <= i, j <= N).
② degree(1) as small as possible.
For example, when N = 3, there are two possible answers: