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B. Odd sum

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputYou are given sequence *a*_{1}, *a*_{2}, ..., *a*_{n} of integer numbers of length *n*. Your task is to find such subsequence that its sum is odd and maximum among all such subsequences. It's guaranteed that given sequence contains subsequence with odd sum.

Subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements.

You should write a program which finds sum of the best subsequence.

Input

The first line contains integer number *n* (1 ≤ *n* ≤ 10^{5}).

The second line contains *n* integer numbers *a*_{1}, *a*_{2}, ..., *a*_{n} ( - 10^{4} ≤ *a*_{i} ≤ 10^{4}). The sequence contains at least one subsequence with odd sum.

Output

Print sum of resulting subseqeuence.

Examples

Input

4

-2 2 -3 1

Output

3

Input

3

2 -5 -3

Output

-1

Note

In the first example sum of the second and the fourth elements is 3.

Codeforces (c) Copyright 2010-2017 Mike Mirzayanov

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