#include <string>
#include <iostream>
#include <math.h>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <map>
#include <set>
typedef long long ll;
const int mod=1e9+7;
#define lol(i,n) for(int i=0;i<n;i++)

using namespace std;
int n,a[110],s=0;
int main() {
    cin >>n;
    lol(i,n){
        cin >>a[i];
        s+=a[i];
    }
    if(s%2==0)cout << s/2<< endl;
    else{
        sort(a,a+n);
        lol(i,n){
            if(a[i]%2==1){
                s-=a[i];
                cout <<s/2<< endl;
                return 0;
            }
        }
    }
}

