Giới thiệu
include<bits/stdc++.h>
define mod 1000000007
using namespace std;
int n;
long long k,le,chan,res = -1;
bool xh;
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
ifndef ONLINE_JUDGE
define ONLINE_JUDGE
freopen("Test.inp","r",stdin);
freopen("Test.out","w",stdout);
endif // ONLINE_JUDGE
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> k;
if(k % 2)
res = max(res,le+k);
else
res = max(res,chan+k);
if(k % 2)
le = max(le,k);
else
chan = max(chan,k);
if (!k) xh = 1;
}
if (n == 2 && !((!(chan || xh))^(!(le))))
cout << -1;
else
cout << res;
return 0;
}