### Maximum sum

Time Limit: 1000 ms Memory Limit: 32768 KiB

#### Problem Description

Given a set of n integers: A={a1, a2,..., an}, we define a function d(A) as below:

#### Input

The input consists of T(<=30) test cases. The number of test cases (T) is given in the first line of the input.

Each test case contains two lines. The first line is an integer n(2<=n<=50000). The second line contains n integers: a1, a2, ..., an. (|ai| <= 10000).There is an empty line after each case.

#### Output

Print exactly one line for each test case. The line should contain the integer d(A).

#### Sample Input

1

10
1 -1 2 2 3 -3 4 -4 5 -5

#### Sample Output

13

#### Hint

poj2479 有链接提示的题目请先去链接处提交程序，AC后提交到SDUTOJ中，以便查询存档。 In the sample, we choose {2,2,3,-3,4} and {5}, then we can get the answer. Huge input,scanf is recommended.

#### Source

POJ Contest,Author:Mathematica@ZSU