#include <iostream>
#include <bitset>
using namespace std;

bitset<2000001> b;
bitset<2000001> e;
bitset<2000001> c;

int main()
{
    int n;
    cin >> n;
    b.set(0, true);
    int s = 0;
    for (int i = 0; i < n; i++)
    {
        int a;
        cin >> a;
        s += a;
        c = b << a;
        e |= b & c;
        b |= c;
    }
    for (int i = 1; i * 2 < s; i++)
    {
        if (e[i])
        {
            cout << s - i * 2 << endl;
            return 0;
        }
    }
    cout << -1 << endl;
}