CF772B.Volatile Kite

普及/提高-

通过率:0%

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题目描述

You are given a convex polygon PP with nn distinct vertices p1,p2,...,pnp_{1},p_{2},...,p_{n} . Vertex pip_{i} has coordinates (xi,yi)(x_{i},y_{i}) in the 2D plane. These vertices are listed in clockwise order.

You can choose a real number DD and move each vertex of the polygon a distance of at most DD from their original positions.

Find the maximum value of DD such that no matter how you move the vertices, the polygon does not intersect itself and stays convex.

输入格式

The first line has one integer nn ( 4<=n<=10004<=n<=1000 ) — the number of vertices.

The next nn lines contain the coordinates of the vertices. Line ii contains two integers xix_{i} and yiy_{i} ( 109<=xi,yi<=109-10^{9}<=x_{i},y_{i}<=10^{9} ) — the coordinates of the ii -th vertex. These points are guaranteed to be given in clockwise order, and will form a strictly convex polygon (in particular, no three consecutive points lie on the same straight line).

输出格式

Print one real number DD , which is the maximum real number such that no matter how you move the vertices, the polygon stays convex.

Your answer will be considered correct if its absolute or relative error does not exceed 10610^{-6} .

Namely, let's assume that your answer is aa and the answer of the jury is bb . The checker program will consider your answer correct if .

输入输出样例

  • 输入#1

    4
    0 0
    0 1
    1 1
    1 0
    

    输出#1

    0.3535533906
    
  • 输入#2

    6
    5 0
    10 0
    12 -4
    10 -8
    5 -8
    3 -4
    

    输出#2

    1.0000000000
    

说明/提示

Here is a picture of the first sample

Here is an example of making the polygon non-convex.

This is not an optimal solution, since the maximum distance we moved one point is 0.4242640687≈0.4242640687 , whereas we can make it non-convex by only moving each point a distance of at most 0.3535533906≈0.3535533906 .

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