#include <bits/stdc++.h>
using namespace std;
const int N = 808;
const int INF = 0x3f3f3f3f;
long long a[N], f[N];
int maxn = -INF;
int main() {
  ios::sync_with_stdio(false);
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  int t;
  for (int i = 1; i <= n; i++) {
    t = 0;
    for (int j = i; j <= n; j++) {
      t ^= a[j];
      maxn = max(t, maxn);
    }
  }
  cout << maxn << endl;
  return 0;
}
