cf 797B

#include<bits\stdc++.h>

using namespace std;

int main()
{
    int n;
    scanf("%d", &n);

    int a[n], i, sum = 0;
    for(i = 0; i < n; i++) scanf("%d", &a[i]);

    for(i = 0; i < n; i++)
    {
        if(a[i] > 0) sum += a[i];
    }

    if(sum % 2 != 0) printf("%d\n", sum);
    else
    {
        sort(a, a + n, greater<int>());

        int val1 = 99999, idx = -1;
        for(i = 0; i < n; i++)
        {
            if(a[i] < 0 && a[i] % 2 != 0)
            {
                idx = i;
                break;
            }
        }
        if(idx >= 0)
        {
            val1 = a[idx];
            val1 = -val1;
        }

        sort(a, a + n);
        int val2 = 99999;
        idx = -1;
        for(i = 0; i < n; i++)
        {
            if(a[i] > 0 && a[i] % 2 != 0)
            {
                idx = i;
                break;
            }
        }
        if(idx >= 0) val2 = a[idx];
        //int f_val = min(val2, -val1);
        //printf("v1 %d v2 %d\n", val1, val2);
        printf("%d\n", sum - min(val1, val2));
    }
}