#include <bits/stdc++.h>

using namespace std;

int n, t;
vector <int> v;

int cnt[31];

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

    cin >> n;
    for (int i = 0; i < n; i++)
    {
        cin >> t;
        for (int j = 0; j <= 30; j++)
        {
            if ((t & (1LL << j)))
            {
                cnt[j]++;
            }
        }
        v.push_back(t);
    }

    long long int x = 0;
    
    for (int j = 30; j >= 0; j--)
    {
        if (cnt[j] == n)
        {
            x += (1LL << j);
        }
        else
        {
            long long int val0 = 0;
            long long int val1 = 0;
            for (int i = 0; i < n; i++)
            {
                if ((v[i] & (1LL << j)))
                {
                    val1 = max(val1, v[i] % (1LL << j));
                }
                else
                {
                    val0 = max(val0, v[i] % (1LL << j));
                }
            }
            if (val0 < val1)
            {
                x += (1LL << j);
            }
        }
    }

    long long int res = 0;

    for (int i = 0; i < n; i++)
    {
        res = max(res, (v[i] ^ x));
    }

    cout << res << '\n';

    return 0;
}