#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
#include <math.h>
#include <string.h>
#include <map>
#include <numeric>
#include <random>
#include <queue>
#include <deque>
#include <tuple>
#include <iomanip>
#include <iterator>
#include <functional>

using namespace std;
typedef long long ll;

const int INF = (1 << 30) - 1;
const ll INFLL= (1LL << 61) - 1;
const int MOD = 1000000007;
#define ALL(a) (a).begin(),(a).end()
#define rALL(a) (a).rbegin(),(a).rend()
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  int N;
  cin>>N;
  vector<int> A(N);
  REP(i,N)cin>>A[i];
  vector<int> nums(N,0);
  REP(i,N)nums[i]=i/2;

  int ans=0;
  do {
    vector<int>AA(N/2);
    REP(i,N){
      AA[nums[i]]+=A[i];
    }
    int tmp=0;
    REP(i,N/2){
      tmp^=AA[i];
    }
    ans=max(tmp,ans);
  } while (std::next_permutation(nums.begin(), nums.end()));

  cout<<ans<<endl;

}