#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); i ++)
using namespace std;
using ll = long long;
using PL = pair<ll,ll>;
using P = pair<int,int>;
constexpr int INF = 1000000000;
constexpr long long HINF = 1000000000000000;
constexpr long long MOD = 1000000007;
constexpr double EPS = 1e-4;
constexpr double PI = 3.14159265358979;
const int MAXN = 200005;

int main() {
    int N; cin >> N;
    vector<ll> A(N);
    rep(i,N) cin >> A[i];
    ll ret = 0;
    rep(i,N) {
        ret ^= A[i];
        ret ^= A[i];
    }
    ll ans = 0;
    rep(i,N)for(int j = i + 1;j < N;j++) {
        ans = max(ans,ret^A[i]^A[j]);
    }
    cout << ans << endl; 
    return 0;
}