#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<cmath>
#include<map>
#define int long long
using namespace std;
int a[114];
signed main() {
	int n, cnt = 0;
	cin >> n;
	for (int i = 0; i < n; i++)cin >> a[i];
	for (int i = 0; i < n; i++) {
		cnt += a[i];
	}
	if (cnt % 2 == 0) {
		cout << cnt / 2 << endl;
	}
	else {
		sort(a, a + n);
		for (int i = 0; i < n; i++) {
			if (a[i] % 2 == 0)continue;
			cnt -= a[i];
			if (cnt % 2 == 0)break;
		}
		cout << cnt / 2 << endl;
	}
}
