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### Problem

### Input

### Output

### Limits

#### Small dataset

#### Large dataset

### Sample

The kitchen at the Infinite House of Pancakes has just received an order for
a stack of **K** pancakes! The chef currently has **N** pancakes
available, where **N** ≥ **K**. Each pancake is a cylinder, and
different pancakes may have different radii and heights.

As the sous-chef, you must choose **K** out of the **N**
available pancakes, discard the others, and arrange those **K** pancakes
in a stack on a plate as follows. First, take the pancake that has the
largest radius, and lay it on the plate on one of its circular faces. (If
multiple pancakes have the same radius, you can use any of them.) Then, take
the remaining pancake with the next largest radius and lay it on top of that
pancake, and so on, until all **K** pancakes are in the stack and the
centers of the circular faces are aligned in a line perpendicular to the
plate, as illustrated by this example:

You know that there is only one thing your diners love as much as they love pancakes: syrup! It is best to maximize the total amount of exposed pancake surface area in the stack, since more exposed pancake surface area means more places to pour on delicious syrup. Any part of a pancake that is not touching part of another pancake or the plate is considered to be exposed.

If you choose the **K** pancakes optimally, what is the largest total
exposed pancake surface area you can achieve?

The first line of the input gives the number of test cases, **T**.
**T** test cases follow. Each begins with one line with two integers
**N** and **K**: the total number of available pancakes, and the size
of the stack that the diner has ordered. Then, **N** more lines follow.
Each contains two integers **R _{i}** and

For each test case, output one line containing `Case #x: y`

,
where `x`

is the test case number (starting from 1) and
`y`

is the maximum possible total exposed pancake surface area, in
millimeters squared. `y`

will be considered correct if it is
within an absolute or relative error of 10^{-6} of the correct
answer. See the FAQ for an
explanation of what that means, and what formats of real numbers we accept.

1 ≤ **T** ≤ 100.

1 ≤ **K** ≤ **N**.

1 ≤ **R _{i}** ≤ 10

1 ≤

1 ≤ **N** ≤ 10.

1 ≤ **N** ≤ 1000.

Input |
Output |

4 2 1 100 20 200 10 2 2 100 20 200 10 3 2 100 10 100 10 100 10 4 2 9 3 7 1 10 1 8 4 |
Case #1: 138230.076757951 Case #2: 150796.447372310 Case #3: 43982.297150257 Case #4: 625.176938064 |

In Sample Case #1, the "stack" consists only of one pancake. A stack of just
the first pancake would have an exposed area of π ×
**R _{0}**

In Sample Case #2, we can use both of the same pancakes from case #1. The
first pancake contributes its top area and its side, for a total of 14000π
mm^{2}. The second pancake contributes some of its top area (the
part not covered by the first pancake) and its side, for a total of 34000π
mm^{2}. The combined exposed surface area is 48000π
mm^{2}.

In Sample Case #3, all of the pancakes have radius 100 and height 10. If we
stack two of these together, we effectively have a single new cylinder of
radius 100 and height 20. The exposed surface area is 14000π
mm^{2}.

In Sample Case #4, the optimal stack uses the pancakes with radii of 8 and 9.