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CF1778A.Flip Flop Sum
Flip Flop Sum
You are given an array of integers . The integers are either or . You have to perform the following operation exactly once on the array :
- Choose an index () and flip the signs of and . Here, flipping the sign means will be and will be .
What is the maximum possible value of after applying the above operation?
Input
Each test contains multiple test cases. The first line contains the number of test cases (). Description of the test cases follows.
The first line of each test case contains a single integer (), the length of the array .
The next line contains integers ( or ).
The sum of over all cases doesn't exceed .
Output
For each test case, print the maximum possible sum of the array you can get in a separate line.
Note
In the first case, we can choose index and flip the signs of and . After this operation, the sum will be . We can't make the sum larger than this.
In the third case, the only option is to choose the index .
Samples
4
5
-1 1 1 -1 -1
5
1 1 -1 -1 -1
2
1 1
4
1 -1 -1 1
3
3
-2
4
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