Migrated from Lutece 399 Refraction I

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Description

Refraction is a common phenomena in our life. Now ,comes a problem. Give you a kind of liquid and its refractive index, you should calculate the focus of the light on the ground(Point $T$ in the picture below).

To let the problem easier,we assume that the air's refractive index is always $1$. As the picture below,the light source is always in the air(the point $S$ in the picture). We assume the $Y$ coordinate of ground level is $0$.

Input

The first line of the data contains a number $T$($1\leq T\leq 500$), indicating the total number of test cases. Each test case consists of $2$ lines .The first line contains $4$ numer $x_1,y_1,x_2,y_2$, indicating the coordinate of the light and the coordinate of the direction respectively. The second line contains $2$ numbers $n$, $H$, indicating the refractive index of the liquid and the depth of the liquid.

Output

For each test case, write a single float numbers $x$ on a single line, indicating the $X$ coordinate of the focus,retain $3$ digits after the decimal point.

If there is not focus on the ground ,just output Impossible on a single line.

Samples

3
3 6 0 6
1.35 3
3 6 0 3
1.35 3
3 6 3 3
1.35 3

Impossible
-1.845
3.000

Resources

10th SCU Programming Contest Final