## Problem Description

Oaiei likes Geometry very much. The charm of Geometry lies in the fact that only using some simple straight line or curve can construct many wonderful graphics.
If you know the edge of the square is a, oaiei can quickly calculate the area of the square is a * a; if you know the edge of the rectangular is a and b respectively, oaiei can quickly calculate the area of the rectangular is a * b.

If you know the four vertices of the quadrilateral, can you help oaiei estimate whether the quadrilateral is parallelogram or not. If the quadrilateral is parallelogram, you should calculate the area of the parallelogram.

## 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. The absolute value of the coordinates are not exceed 1000.

## Output

For each test, if the quadrilateral is parallelogram, you should output the area with accuracy 10^(-3). If the quadrilateral is not parallelogram, you should output “No” (quotes for clarity only).

## Sample Input

0.0000 0.0000
2.0000 1.0000
1.0000 3.0000
3.0000 4.0000
0.0000 0.0000
2.0000 1.0000
1.0000 3.0000
3.0000 3.0000

## Sample Output

5.000
No

## Source

Summer Training Qualification I