Problems
Polygon
Polygon
The military training ground has the shape of an n - gon. If one of the vertices is deleted, then the polygon becomes convex. Find the number of this vertex.
Input
The first line contains the number of vertices n (4 ≤ n ≤ 20) in polygon. Each of the next n lines contains two numbers - the coordinates of successive vertices of a polygon.
Output
Print the number of required vertex.
Input example #1
5 3 7 7 3 3 3 0 0 1 4.5
Output example #1
3