#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;


const int N = 1e5 + 10;
int son[N][2], cnt[N], idx;
int n;
int a[N];

vector<int> get2(int x){
    vector<int> a;
    while(x){
        a.push_back(x & 1);
        x >>= 1;
    }

    reverse(a.begin(), a.end());
    return a;
}

void insert(int x){
    auto a = get2(x);
    int p = 0;
    for(int i = 0; i < a.size(); ++ i){
        int u = a[i];
        if(!son[p][u]) son[p][u] = ++ idx;
        p = son[p][u];
    }
    cnt[p] = x;
}

int query(int x){
    auto a = get2(x);
    int p = 0;
    for(int i = 0; i < a.size(); ++ i){
        int u = a[i]; // u = 0|u = 1
        if(u == 0) p = son[p][u + 1] ? son[p][u + 1] : son[p][u];
        if(u == 1) p = son[p][u - 1] ? son[p][u - 1] : son[p][u];
    }
    return cnt[p];
}



int main(){
    cin >> n;

    int ans = 0;
    for(int i = 1; i <= n; ++ i){
        cin >> a[i];
        insert(a[i]);
    }

    for(int i = 1; i <= n; ++ i){
        ans = max(ans, a[i] ^ query(a[i]));
    }

    cout << ans;

    return 0;
}