#include <bits/stdc++.h>
#include <cassert>
using namespace std;
using ll = long long;
// #define int ll

using uintT = uint64_t;

int n;
constexpr int MAXN = 100'000;
uintT a[MAXN];

signed main() {
    cin >> n;
    uintT ans = 0;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        ans |= a[i];
    }
    sort(a, a + n);
    for (int b = 0; b < 62; b++) {
        uintT bb = (uintT(1) << b);
        if (ans & bb) continue;
        uintT acc = 0;
        for (int i = n - 1; i >= 0; i--) {
            uintT x = (a[i] & (bb - 1));
            acc += x;
        }
        if (acc >= bb) {
            ans |= bb;
        }
    }
    cout << ans << endl;
}