Symmetric Points Check

Given n points on a 2D plane, determine whether the set of points is symmetric with respect to the vertical line \(x=0\). In other words, for every point \((x, y)\) in the set, its mirror image \((-x, y)\) must also appear.

The input begins with an integer n (\(n \ge 1\)), the number of points. This is followed by n lines, each containing two space‐separated integers representing the coordinates \(x\) and \(y\) of a point.

If every point satisfies the condition that its mirror \((-x, y)\) exists, output Yes; otherwise, output No.

inputFormat

Input is given via standard input (stdin). The first line contains a single integer n. Each of the following n lines contains two space-separated integers x and y representing the coordinates of a point.

outputFormat

Output a single line to standard output (stdout) containing either Yes if the set of points is symmetric about \(x=0\), or No if it is not.

3
1 2
-1 2
0 2

Yes