对每个 $\forall \ A_i$，考虑从高位到低位，$\forall \ i \in [\text{highbit} \to \text{lowbit}]$
要找到这样的一个 $A_j$，满足 $A_j$ 尽可能多的高位与 $A_i$ 不同，这样异或的高位就有尽可能多的 $1$

• 将所有数按位插入 $\text{trie}$ 中，$p = 1$ 初始化为根节点

• 遍历每个 $A_i$，$i \in [\text{highbit} \to \text{lowbit}]$ 检查每一位

• 如果 $\text{trie}(p, !i) \neq 0$，那么顺着 $\text{trie}(p, !i)$ 走
  并且 $res += (1 << i)$

• 否则沿着 $\text{trie}(p, i)$ 走

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <vector>
#include <stack>
#include <map>
#include <set>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <bitset>
#include <assert.h>
#include <unordered_map>

using namespace std;
typedef long long ll;

#define Cmp(a, b) memcmp(a, b, sizeof(b))
#define Cpy(a, b) memcpy(a, b, sizeof(b))
#define Set(a, v) memset(a, v, sizeof(a))
#define debug(x) cout << #x << ": " << x << endl
#define _forS(i, l, r) for(set<int>::iterator i = (l); i != (r); i++)
#define _rep(i, l, r) for(int i = (l); i <= (r); i++)
#define _for(i, l, r) for(int i = (l); i < (r); i++)
#define _forDown(i, l, r) for(int i = (l); i >= r; i--)
#define debug_(ch, i) printf(#ch"[%d]: %d\n", i, ch[i])
#define debug_m(mp, p) printf(#mp"[%d]: %d\n", p->first, p->second)
#define debugS(str) cout << "dbg: " << str << endl;
#define debugArr(arr, x, y) _for(i, 0, x) { _for(j, 0, y) printf("%c", arr[i][j]); printf("\n"); }
#define _forPlus(i, l, d, r) for(int i = (l); i + d < (r); i++)
#define lowbit(i) (i & (-i))
#define MPR(a, b) make_pair(a, b)

pair<int, int> crack(int n) {
    int st = sqrt(n);
    int fac = n / st;
    while (n % st) {
        st += 1;
        fac = n / st;
    }

    return make_pair(st, fac);
}

inline ll qpow(ll a, int n) {
    ll ans = 1;
    for(; n; n >>= 1) {
        if(n & 1) ans *= 1ll * a;
        a *= a;
    }
    return ans;
}

template <class T>
inline bool chmax(T& a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

ll gcd(ll a, ll b) {
    return b == 0 ? a : gcd(b, a % b);
}

ll ksc(ll a, ll b, ll mod) {
    ll ans = 0;
    for(; b; b >>= 1) {
        if (b & 1) ans = (ans + a) % mod;
        a = (a * 2) % mod;
    }
    return ans;
}

ll ksm(ll a, ll b, ll mod) {
    ll ans = 1 % mod;
    a %= mod;

    for(; b; b >>= 1) {
        if (b & 1) ans = ksc(ans, a, mod);
        a = ksc(a, a, mod);
    }

    return ans;
}

template <class T>
inline bool chmin(T& a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
bool lexSmaller(vector<T> a, vector<T> b) {
    int n = a.size(), m = b.size();
    int i;
    for(i = 0; i < n && i < m; i++) {
        if (a[i] < b[i]) return true;
        else if (b[i] < a[i]) return false;
    }
    return (i == n && i < m);
}

// ============================================================== //

const int maxn = 3100000 + 5;
const int N = 1e5 + 5;
int n, a[N];

class Trie {
public:
    int tot;
    int t[maxn][2];

    Trie() {
        tot = 1;
        memset(t, 0, sizeof t);
    }

    void insert(int x) {
        int p = 1;
        for (int i = 30; i >= 0; i--) {
            int c = (x >> i & 1);
            if (t[p][c] == 0) t[p][c] = ++tot;
            p = t[p][c];
        }
    }
    int query(int x) {
        int res = 0, p = 1;
        for (int i = 30; i >= 0; i--) {
           int c = x >> i & 1;
           if (t[p][!c]) {
               res += (1<<i);
               p = t[p][!c];
           }
           else p = t[p][c];
        }
        return res;
    }
};

Trie trie;

int main() {
    freopen("input.txt", "r", stdin);
    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        scanf("%d", &a[i]);
        trie.insert(a[i]);
    }

    int res = 0;
    for (int i = 0; i < n; i++) res = max(res, trie.query(a[i]));
    printf("%d\n", res);
}