#include <bits/stdc++.h>

using namespace std;

using ll = long long;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    vector<ll> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a.begin(), a.end());

    ll ans = 0;
    do {
        ll s = 0;
        for (int i = 0; i < n / 2; i++) s ^= (a[i] + a[i + n / 2]);
        ans = max(ans, s);
        reverse(a.begin() + n / 2, a.end());
    } while (next_permutation(a.begin(), a.end()));
    cout << ans << endl;
    return 0;
}