// competitive-verifier: PROBLEM
#include <cassert>
/**
 * @brief 2分トライ木
 * @see https://kazuma8128.hatenablog.com/entry/2018/05/06/022654
 *
 * @tparam T 要素の型
 * @tparam B ビットサイズ
 */
template <class T, int B = 31>
struct binary_trie {
  private:
    struct _node {
        using pointer = _node *;
        int count;
        pointer ch[2];
        _node() : count(), ch{nullptr, nullptr} {}
    };
  public:
    using node_ptr = typename _node::pointer;
    constexpr binary_trie() : root(nullptr) {}
    T operator[](int k) const {
        assert(0 <= k && k < size());
        return get(root, k);
    }
    T at(int k) const { return operator[](k); }
    T get(int k) const { return operator[](k); }
    T kth_element(int k) const { return operator[](k); }
    constexpr bool empty() const { return !root; }
    constexpr int size() const { return empty() ? 0 : root->count; }
    void insert(T val) {
        if (!count(val)) root = insert(root, val);
    }
    void erase(T val) {
        if (count(val)) root = erase(root, val);
    }
    T max_element(T bias = 0) const { return get_min(root, ~bias); }
    T min_element(T bias = 0) const { return get_min(root, bias); }
    int lower_bound(T val) const { return count_lower(root, val); }
    int upper_bound(T val) const { return count_lower(root, val + 1); }
    int count(T val) const {
        if (!root) return 0;
        node_ptr node = root;
        for (int i = B - 1; i >= 0; i--) {
            node = node->ch[val >> i & 1];
            if (!node) return 0;
        }
        return node->count;
    }
  private:
    node_ptr root;
    node_ptr insert(node_ptr node, T val, int b = B - 1) {
        if (!node) node = new _node();
        ++node->count;
        if (b < 0) return node;
        bool f = val >> b & 1;
        node->ch[f] = insert(node->ch[f], val, b - 1);
        return node;
    }
    node_ptr erase(node_ptr node, T val, int b = B - 1) {
        assert(node);
        --node->count;
        if (!node->count) return nullptr;
        if (b < 0) return node;
        bool f = val >> b & 1;
        node->ch[f] = erase(node->ch[f], val, b - 1);
        return node;
    }
    T get_min(node_ptr node, T val, int b = B - 1) const {
        assert(node);
        if (b < 0) return 0;
        bool f = val >> b & 1;
        f ^= !node->ch[f];
        return get_min(node->ch[f], val, b - 1) | ((T)f << b);
    }
    T get(node_ptr node, int k, int b = B - 1) const {
        if (b < 0) return 0;
        int m = node->ch[0] ? node->ch[0]->count : 0;
        return k < m ? get(node->ch[0], k, b - 1) : get(node->ch[1], k - m, b - 1) | ((T)1 << b);
    }
    int count_lower(node_ptr node, T val, int b = B - 1) const {
        if (!node || b < 0) return 0;
        bool f = val >> b & 1;
        return (f && node->ch[0] ? node->ch[0]->count : 0) + count_lower(node->ch[f], val, b - 1);
    }
};
/**
 * @brief 多重2分トライ木
 * @see https://kazuma8128.hatenablog.com/entry/2018/05/06/022654
 *
 * @tparam T 要素の型
 * @tparam B ビットサイズ
 */
template <class T, int B = 31>
struct multi_binary_trie {
  private:
    struct _node {
        using pointer = _node *;
        int count;
        pointer ch[2];
        _node() : count(), ch{nullptr, nullptr} {}
    };
  public:
    using node_ptr = typename _node::pointer;
    multi_binary_trie() : root(nullptr) {}
    T operator[](int k) const {
        assert(0 <= k && k < size());
        return get(root, k);
    }
    T at(int k) const { return operator[](k); }
    T get(int k) const { return operator[](k); }
    T kth_element(int k) const { return operator[](k); }
    constexpr int size() const { return root ? root->count : 0; }
    constexpr bool empty() const { return !root; }
    void insert(T val) { root = insert(root, val); }
    void erase(T val) {
        if (count(val)) root = erase(root, val);
    }
    T max_element(T bias = 0) const { return get_min(root, ~bias); }
    T min_element(T bias = 0) const { return get_min(root, bias); }
    int lower_bound(T val) { return count_lower(root, val); }
    int upper_bound(T val) { return count_lower(root, val + 1); }
    int count(T val) const {
        if (!root) return 0;
        node_ptr node = root;
        for (int i = B - 1; i >= 0; i--) {
            node = node->ch[val >> i & 1];
            if (!node) return 0;
        }
        return node->count;
    }
  private:
    node_ptr root;
    node_ptr insert(node_ptr node, T val, int b = B - 1) {
        if (!node) node = new _node();
        ++node->count;
        if (b < 0) return node;
        bool f = val >> b & 1;
        node->ch[f] = insert(node->ch[f], val, b - 1);
        return node;
    }
    node_ptr erase(node_ptr node, T val, int b = B - 1) {
        assert(node);
        --node->count;
        if (!node->count) return nullptr;
        if (b < 0) return node;
        bool f = val >> b & 1;
        node->ch[f] = erase(node->ch[f], val, b - 1);
        return node;
    }
    T get_min(node_ptr node, T val, int b = B - 1) const {
        assert(node);
        if (b < 0) return 0;
        bool f = val >> b & 1;
        f ^= !node->ch[f];
        return get_min(node->ch[f], val, b - 1) | ((T)f << b);
    }
    T get(node_ptr node, int k, int b = B - 1) const {
        if (b < 0) return 0;
        int m = node->ch[0] ? node->ch[0]->count : 0;
        return k < m ? get(node->ch[0], k, b - 1) : get(node->ch[1], k - m, b - 1) | ((T)1 << b);
    }
    int count_lower(node_ptr node, T val, int b = B - 1) {
        if (!node || b < 0) return 0;
        bool f = val >> b & 1;
        return (f && node->ch[0] ? node->ch[0]->count : 0) + count_lower(node->ch[f], val, b - 1);
    }
};
#ifdef ATCODER
#pragma GCC target("sse4.2,avx512f,avx512dq,avx512ifma,avx512cd,avx512bw,avx512vl,bmi2")
#endif
#pragma GCC optimize("Ofast,fast-math,unroll-all-loops")
#include <bits/stdc++.h>
#ifndef ATCODER
#pragma GCC target("sse4.2,avx2,bmi2")
#endif
template <class T, class U>
constexpr bool chmax(T &a, const U &b) {
    return a < (T)b ? a = (T)b, true : false;
}
template <class T, class U>
constexpr bool chmin(T &a, const U &b) {
    return (T)b < a ? a = (T)b, true : false;
}
constexpr std::int64_t INF = 1000000000000000003;
constexpr int Inf = 1000000003;
constexpr double EPS = 1e-7;
constexpr double PI = 3.14159265358979323846;
#define FOR(i, m, n) for (int i = (m); i < int(n); ++i)
#define FORR(i, m, n) for (int i = (m)-1; i >= int(n); --i)
#define FORL(i, m, n) for (int64_t i = (m); i < int64_t(n); ++i)
#define rep(i, n) FOR (i, 0, n)
#define repn(i, n) FOR (i, 1, n + 1)
#define repr(i, n) FORR (i, n, 0)
#define repnr(i, n) FORR (i, n + 1, 1)
#define all(s) (s).begin(), (s).end()
struct Sonic {
    Sonic() {
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
        std::cout << std::fixed << std::setprecision(20);
    }
    constexpr void operator()() const {}
} sonic;
using namespace std;
using ll = std::int64_t;
using ld = long double;
template <class T, class U>
std::istream &operator>>(std::istream &is, std::pair<T, U> &p) {
    return is >> p.first >> p.second;
}
template <class T>
std::istream &operator>>(std::istream &is, std::vector<T> &v) {
    for (T &i : v) is >> i;
    return is;
}
template <class T, class U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &p) {
    return os << '(' << p.first << ',' << p.second << ')';
}
template <class T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &v) {
    for (auto it = v.begin(); it != v.end(); ++it) os << (it == v.begin() ? "" : " ") << *it;
    return os;
}
template <class Head, class... Tail>
void co(Head &&head, Tail &&...tail) {
    if constexpr (sizeof...(tail) == 0) std::cout << head << '\n';
    else std::cout << head << ' ', co(std::forward<Tail>(tail)...);
}
template <class Head, class... Tail>
void ce(Head &&head, Tail &&...tail) {
    if constexpr (sizeof...(tail) == 0) std::cerr << head << '\n';
    else std::cerr << head << ' ', ce(std::forward<Tail>(tail)...);
}
void Yes(bool is_correct = true) { std::cout << (is_correct ? "Yes\n" : "No\n"); }
void No(bool is_not_correct = true) { Yes(!is_not_correct); }
void YES(bool is_correct = true) { std::cout << (is_correct ? "YES\n" : "NO\n"); }
void NO(bool is_not_correct = true) { YES(!is_not_correct); }
void Takahashi(bool is_correct = true) { std::cout << (is_correct ? "Takahashi" : "Aoki") << '\n'; }
void Aoki(bool is_not_correct = true) { Takahashi(!is_not_correct); }
int main(void) {
    int n;
    cin >> n;
    vector<int> a(n);
    cin >> a;
    binary_trie<int> bt;
    rep (i, n) bt.insert(a[i]);
    int ans = 0;
    rep (i, n) {
        chmax(ans, bt.max_element(a[i]) ^ a[i]);
    }
    co(ans);
    return 0;
}