Hitmonchan and Hitmonlee one day came across a large number of sticks. Unable to think of anything useful to do with them, they try to solve an interesting problem- what is the maximum area of a rectangle that they can make using those rectangles?

More succinctly, given an array A of N integers which represents stick lengths , we need to report the maximal area over all the rectangles that we can form with the given sticks without breaking any.
Note-Only 4 sticks are needed to form a rectangle.

Input:

First line consists of t , the number of test cases. For each test case there is an integer N and then the entries of array A[i] denoting the length of sticks, in each separate line.

Output:
The maximum area of rectangle that can be formed using the sticks. In case no rectangle forms ouptut must be -1.

Constraints:
1<=t<=10000
1<=N<=1000
1<=A[i]<=1000 for all i