#include<iostream>
#include<algorithm>

using namespace std;

const int N = 100010;

int a[N], cst[N];

int son[N * 30][1], idx;

void Insert(int x)
{
    int q = 0;
    for(int i = 30; i >= 0 ; i --)
    {
        int u = x >> i & 1;
        if(!son[q][u]) son[q][u] = ++ idx;
        q = son[q][u];
    }
    cst[q] ++;
}

int Search(int x)
{
    int q = 0, res = 0;
    for(int i = 30; i >= 0; i --)
    {
        int u = x >> i & 1;
        if(son[q][!u]){
            res += 1 << i;
            q = son[q][!u];
        }
        else{
            q = son[q][u];
        }
    }
    return res;
}

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

    int r = 0;
    for(int i = 0; i < n; i ++)
    {
        r = max(r, Search(a[i]));
    }
    printf("%d", r);
    return 0;
}