write a program in c++ .. if n points are given. Implement an O(n)-time algorithm to find out if the first point is a vertex of the convex hull of the points. The algorithm must verify if the dual of the first point is on the upper or lower envelopes in the dual plane. The input starts with the number of points and then their coordinates. If the first point is a hull vertex, the output is 1, and otherwise 0.

note :1 . the input of vertices and thier coordinate must be enter by user

2 test the program in these sample

nomber of vertices = 4

thier coordinate

2 1

0 2

2 0

4 2