#include<bits/stdc++.h>
#define rep(i,n,m) for(int i = (n); i <(m); i++)
#define rrep(i,n,m) for(int i = (n) - 1; i >=(m); i--)
using namespace std;
using ll = long long;
using pii = pair<int, int>;

ll search(vector<int> a, ll power)
{
    if (a.size() == 0)
        return power;
    
    ll res = 0;
    ll one = a[0];
    a.erase(a.begin());
    rep(i, 0, a.size())
    {
        vector<int> aa = a;
        aa.erase(aa.begin() + i);
        res = max(res, search(aa, power ^ (one+a[i])));
    }
    return res;
}

int main()
{
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, 0, n) cin >> a[i];

    cout << search(a, 0) << endl;
    return 0;
}