Solve the programming task below in a Python markdown code block.
Chef has an array A of length N. He defines the *alternating sum* of the array as:
S = |A_{1}| - |A_{2}| + |A_{3}| - |A_{4}| + \ldots (-1)^{N-1}\cdot |A_{N}|

Chef is allowed to perform the following operation on the array at most once:
Choose two indices i and j (1 ≤ i <  j ≤ N) and swap the elements A_{i} and A_{j}.

Find the maximum *alternating sum* Chef can achieve by performing the operation at most once.

Note: |X| denotes the absolute value of X. For example, |-4| = 4 and |7| = 7.

------ Input Format ------ 

- The first line will contain T - the number of test cases. Then the test cases follow.
- First line of each test case contains a single integer N - size of the array A.
- Second line of each test case contains N space separated integers - denoting the elements of array A.

------ Output Format ------ 

For each testcase, output in a single line, the maximum *alternating sum* Chef can obtain by performing the operation at most once.

------ Constraints ------ 

$1 ≤ T ≤ 10^{5}$
$2 ≤ N ≤ 10^{5}$
$-10^{9} ≤ A_{i} ≤ 10^{9}$
- Sum of $N$ over all test cases does not exceed $2 \cdot 10^{5}$.

----- Sample Input 1 ------ 
2
2
10 -10
7
-3 -2 -1 0 1 2 3

----- Sample Output 1 ------ 
0
6

----- explanation 1 ------ 
Test Case $1$: One optimal way is to perform no operations. Thus the alternating sum is $|10| - |-10| = 10 - 10 = 0$.

Test Case $2$: One optimal way is to choose $i = 2$ and $j = 5$. After swapping, the array is $[-3, 1, -1, 0, -2, 2, 3]$. The alternating sum in this case is $|-3| - |1| + |-1| - |0| + |-2| - |2| + |3| = 6$.