Pumpkin Pies
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Thanksgiving is coming up and traditionally I'm serving pumpkin pie.  Not 
just one pie, no, I have a number P of them.  F of my friends are coming 
to my party and each of them gets piece(s) of pie.  This could be one 
piece of one pie, but also several small pieces.  A piece can be one 
whole pie.

My friends are very annoying and if one of them gets a bigger piece than 
the others, they start complaining.  Therefore all of them should get 
equally sized (but not necessarily equally shaped) pieces.  Of course, 
I want pieces of pie for myself too, and those pieces should also add
up to the same size.

What is the sum of sizes of the pieces each of us will get? All the pies 
are cylindrical in shape and they all have the same height 1, but the radii 
of the pies can be different.

Input
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One line with a positive integer: the number of test cases. Then for 
each test case:
- One line with two integers P and F with 1 <= P, F <= 100: the number 
  of pies and the number of friends.
- One line with P integers ri with 1 <= ri <= 100: the radii of the pies.

Output
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For each test case, output one line with volume V such that my friends 
and I all get a pie pieces totalling size V.  The answer should be given 
as an integer number (the largest integer number smaller than or equal
to the real answer).

Sample input
------------
3
3 3
4 3 3
1 24
5
10 5
1 4 2 3 4 5 6 5 4 2

Sample output
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26
3
79