#include <fstream>
#include <algorithm>
using namespace std;

ifstream fin("maxxor.in");
ofstream fout("maxxor.out");

const int MAX_N = 100100;

long long v[MAX_N];

int search(int st, int dr, const long long val) {
    int ans = 0;
    while(st <= dr) {
        int mij = (st + dr) / 2;
        if(v[mij] & val) {
            ans = mij;
            dr = mij - 1;
        }
        else {
            st = mij + 1;
        }
    }
    return ans;
}

int solve(int st, int dr, const long long val, int bit) {
    if(v[st] == v[dr]) {
        return st;
    }
    bool p = val & (1LL << bit);
    int poz = search(st, dr, (1LL << bit));
    if(poz == 0 || poz == st) {
        return solve(st, dr, val, bit - 1);
    }

    if(p) {
        return solve(st, poz - 1, val, bit - 1);
    }
    return solve(poz, dr, val, bit - 1);
}

int main() {
    int n;
    fin >> n;
    for(int i = 1; i <= n; i++) {
        fin >> v[i];
    }
    sort(v + 1, v + n + 1);

    long long ans = 0;

    for(int i = 2; i <= n; i++) {
        ans = max(ans, v[solve(1, i - 1, v[i], 62)] ^ v[i]);
    }

    fout << ans;

    return 0;
}