Given a convex polygon in 2D plane. For a point strictly inside the polygon, we can draw segments and get angles , then we say the value of the point is the minimum among the angles. Your task is to find a point strictly inside the polygon with the maximum value and print the maximum value in degrees.

输入描述:

The first line contains one integer , denoting the size of given convex polygon.

Following  lines each contains two integers , denoting the points.

It's guaranteed that the points form a convex polygon and are given counter-clockwise.

输出描述:

Output one line containing one decimal, denoting the answer.

Your answer will be considered to be correct if the relative or absolute error is less than .

4
2 1
-1 1
-1 -1
2 -1

67.38013505195957

The point  can be  and the exact answer is .