#include<iostream>
using namespace std;

int main()
{
    int n, cnt, sum = 0, min = 10000000, a[100];
    
    cin >> n;

    for( int i = 0; i < n; i++ )
    {
        cin >> a[i];
        if( a[i] % 2 == 1 )
        {
            cnt++;
            if( min > a[i] )
                min = a[i];
        }
        sum += a[i];
    }

    if( cnt % 2 == 0 )
        cout << sum / 2 << endl;
    else
        cout << ( sum - min ) / 2 << endl;

    return 0;
}
