#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main() {
    int k;
    cin >> k;
    vector<ll> nums;
    ll temp;
    ll sum{};
    for (int i = 0; i < k; i++) {
        cin >> temp;
        sum += temp;
        nums.push_back(temp);
    }

    int size_sum = __lg(sum);

    ll a, b;
    ll out = nums[0];
    for (int i = 1; i < k; i++) {
        a = nums[i];
        bool hold = false;
        for (int j = 0; j <= 64; j++) {
            if (((a>>j)&1) && ((out>>j)&1)) {hold = true; continue;}
            if (((a>>j)&1) || ((out>>j)&1)) {
                out|=1<<j;
            }
            else {
                if (hold && j <= size_sum) {
                    out|=1<<j;
                }
            }
            hold = false;
        }
    }
    cout << out << '\n';
    return 0;
}