It is a simple task, for N points on the 2D plane, you are supposed to find whether there are three points which could form a isoscelestriangle.
There are several test cases. For each case, the first line is an integer N (3 <= N <= 500) indicating the number of points. N lines follow, each line contains two doubles(not exceed 1000.0), indicating the coordinates of the points.
For each case, if there exists a solution which could form a isosceles triangle, output “YES”, else output “NO”.