CF797B.Odd sum

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题目描述

You 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.

输入格式

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.

输出格式

Print sum of resulting subseqeuence.

输入输出样例

输入#1
```
4
-2 2 -3 1
```
输出#1
```
3
```
输入#2
```
3
2 -5 -3
```
输出#2
```
-1
```

说明/提示

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

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