Shmerulean#10972
Temirulan found a piece of paper of Aidana's favourite color, "Shmerulean". This paper has the shape of a convex polygon, and there are stones placed on its border vertices. Temirulan wants to cut off a piece of the paper and give it to Aidana. However, Aidana only likes rhombuses, from which it is at least possible to build a kite. Help Temirulan to cut the polygon so that the remaining part is a rhombus, and each vertex of the rhombus contains a stone. Either determine how to make such a cut, or state that it is impossible.
The first line contains one integer (3 \le n \le 50), the number of vertices of the polygon. Each of the next lines contains two integers x_i, y_i (-100 \le x_i, y_i \le 100), the coordinates of the -th vertex. The vertices of the polygon are given in clockwise order.
If a solution exists, output pairs of coordinates (in lines), which are the vertices of the rhombus in either clockwise or counterclockwise order. If it is impossible, output -1 in a single line.
Example 1