I have a set of positive integers $S$. Can you find two nonempty,
distinct subsets with the same sum?
Note: A subset is a set that contains only elements from
$S$, and two subsets are
distinct if they do not have exactly the same elements.
Input
The first line of the input gives the number of test cases,
$T$. $T$ test cases follow, one per line.
Each test case begins with $N$, the number of positive integers
in $S$. It is followed by
$N$ distinct positive
integers, all on the same line.
Output
For each test case, first output one line containing
"Case #x:", where $x$ is the case number (starting from
1).

If there are two different subsets of $S$ that have the same sum, then
output these subsets, one per line. Each line should
contain the numbers in one subset, separated by spaces.

If it is impossible, then you should output the string
"Impossible" on a single line.
If there are multiple ways of choosing two subsets with the
same sum, any choice is acceptable.
Limits
No two numbers in $S$
will be equal. $1 \leq T \leq
10$. $N$ is exactly
equal to 20. Each number in $S$ will be a positive integer less
than $10^{5}$.
Sample Input 1 
Sample Output 1 
2
20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
20 120 266 858 1243 1657 1771 2328 2490 2665 2894 3117 4210 4454 4943 5690 6170 7048 7125 9512 9600

Case #1:
1 2
3
Case #2:
3117 4210 4943
2328 2894 7048
