#include <iostream>

using namespace std;

const int N = 100010, M = 3100010;

int a[N];
int son[M][2], idx;

void insert(int x)
{
    int p = 0;
    for (int i = 30; i >= 0; --i)
    {
        int t = x >> i & 1;
        if (!son[p][t]) son[p][t] = ++idx;
        p = son[p][t];
    }
}

int query(int x)
{
    int p = 0, res = 0;
    for (int i = 30; i >= 0; --i)
    {
        int t = x >> i & 1;
        if (son[p][!t]) 
        {
            p = son[p][!t];
            res = res * 2 + 1;
        }
        else 
        {
            p = son[p][t];
            res = res * 2;
        }
    }
    return res;
}

int main()
{
    int n;
    cin >> n;

    for (int i = 0; i < n; ++i) 
    {
        scanf("%d", &a[i]);
        insert(a[i]);
    }

    int res = 0;
    for (int i = 0; i < n; ++i)
        res = max(res, query(a[i]));

    cout << res << endl;

    return 0;
}