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#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <fstream>
#include <cassert>
#include <cstring>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
#include <ctime>
#include <bitset>
#include <random>
#include <complex>

using namespace std;

const int LIM = 100;

mt19937 rng(337);

int solve(vector<int> a) {
    int ans = 0;
    int n = (int)a.size();
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            for (int k = j + 1; k < n; k++) {
                int val = (a[j] & a[k]);
                val |= a[i];
                ans = max(ans, val);
            }
        }
    }
    return ans;
}

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

    int n;
    cin >> n;
    vector<int> a(n);
    for (auto &t : a) {
        cin >> t;
    }
    int ans = 0;
    while ((double)clock() / CLOCKS_PER_SEC < 1.9) {
        vector<int> ind;
        for (int i = 0; i < LIM; i++) {
            ind.push_back(rng() % n);
        }
        sort(ind.begin(), ind.end());
        ind.resize(unique(ind.begin(), ind.end()) - ind.begin());
        vector<int> v;
        for (auto i : ind) {
            v.push_back(a[i]);
        }
        ans = max(ans, solve(v));
    }
    cout << ans << endl;
}