Firebending

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Points: 3
Time limit: 1.0s
Memory limit: 16M

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Problem type
Vincent Massey SS - 2014 Senior Contest #1

Firebending is the element of power. Firebenders use their energy to create bursts of fire in order to overwhelm their opponent. As a result, they want to maximize the value of each fire blast that they shoot. In order to do so, they must revisit the art of mathematics.

You will be given n integers, one per line. For each of the integers, k_i, you can either keep it as k_i, or change it to -k_i. Find the maximum possible final sum of all the integers.

Input Specification

The first line will contain the integer n (1 \le n \le 100\,000).
The next n lines will contain the integers k_i.

Output Specification

The largest possible final sum of the n integers.

Sample Input

3
1
-2
3

Sample Output

6

Explanation

Keep 1.
Change -2 to 2.
Keep 3.
Thus, the answer is 1 + 2 + 3 = 6.


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