#include "bits/stdc++.h"
#define L(o) (o).begin(),(o).end()
#define R(i,n) for(int i=0;i<n;i++)
using namespace std;

int main() {
    int n;cin>>n;
    vector<int> a(n);
    R(i,n)cin>>a[i];
    sort(L(a));
    int r=0;
    do{
        int s=0;
        R(i,n/2) {
            s^=a[i]+a[i+n/2];
        }
        r=max(r,s);
        reverse(a.begin()+n/2,a.end());
    }while(next_permutation(L(a)));
    cout<<r<<endl;
}