#include <bits/stdc++.h>

using namespace std;

using ll = unsigned long long;
using vi = vector<int>;
using pi = pair <int, int>;
using vll = vector<ll>;

void solve ()
{
    int n;
    cin >> n;
    vll a(n);
    for (auto& x : a)
        cin >> x;

    ll res = 0;
    for (int i = 0; i < 64; ++i)
    {
        ll sum = 0;
        for (int j = 0; j < n; ++j)
        {
            sum += (a[j] & ((1ULL << (i + 1)) - 1));
            if (sum >= (1ULL << i))
                break;
        }
        if (sum >= (1ULL << i))
            res |= (1ULL << i);
    }
    cout << res << '\n';
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    solve();
    return 0;
}