﻿ Fuzhou University OnlineJudge ﻿  Problem 1611 Hero's circle

## Problem Description

The hero and oaiei is playing a game now. The hero draws arbitrary quadrilateral in a plane, the four vertices of the quadrilateral are A, B, C, D respectively, and oaiei must draw a circle on the plane, the circle must go through the quadrilateral' four vertices . Can you help oaiei determine whether he can draw a circle through the four points? ## Input

There are multiple tests. For each test, threre contains four lines.

The first line contains two floating-point number Ax Ay, denoting that the coordinate of point A is (Ax, Ay).

The second line contains two floating-point number Bx By, denoting that the coordinate of point B is (Bx, By).

The third line contains two floating-point number Cx Cy, denoting that the coordinate of point C is (Cx, Cy).

The fourth line contains two floating-point number Dx Dy, denoting that the coordinate of point D is (Dx, Dy).

We guarantee that the four points are different and the order are given arbitrarily.

## Output

For each test, if oaiei can draw a circle, then you should output “Yes”, otherwise you should output “No” on a single line（quotes for clarity only）.

## Sample Input

0.000 0.000 1.000 0.000 1.000 1.000 0.000 1.000 0.000 0.000 1.000 0.000 1.000 1.000 2.000 1.000

Yes No

## Source

FOJ月赛-2008年6月 -- Heroes Happen Here

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