Anas has an array $$$a$$$ of an even length $$$n$$$. The array can be partitioned into $$$\frac{n}{2}$$$ pairs such that the two elements in every pair are opposites: one is equal to $$$x$$$ and the other is equal to $$$-x$$$.
Anas removes exactly one element from the array and gives the remaining $$$n-1$$$ elements to Shaban. Determine the value of the removed element.
The order of the remaining elements may be arbitrary.
The first line contains an integer $$$t$$$ ($$$1 \le t \le 10^4$$$) — the number of test cases.
The first line of each test case contains an even integer $$$n$$$ ($$$1 \le n \le 10^5$$$) — the length of the original array.
The second line contains $$$n-1$$$ integers $$$b_1,b_2,\ldots,b_{n-1}$$$ ($$$-10^4 \le b_i \le 10^4$$$) — the elements remaining after Anas removed one element.
It is guaranteed that the given elements were obtained by removing exactly one element from an array that can be partitioned into pairs of opposite elements. The removed element is also between $$$-10^4$$$ and $$$10^4$$$, inclusive.
It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2\cdot 10^5$$$.
For each test case, print one integer — the value of the removed element.
4 2 7 4 5 -5 -9 6 1 -1 4 -4 -123 8 10000 -10000 2 -2 2 -2 42
-7 9 123 -42
In the first test case, the original array was $$$[7,-7]$$$.
In the second test case, adding $$$9$$$ gives the array $$$[5,-5,-9,9]$$$, which can be partitioned into the pairs $$$(5,-5)$$$ and $$$(-9,9)$$$.
