#include <bits/stdc++.h>
using namespace std;
int j, i, a, b, c, k, d, e, f[1005], n, mi, ma;
int main() {
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> f[i];
    ma = max(f[i], ma);
  }
  for (i = 0; i < n - 1; i++)
    for (j = i + 1; j < n; j++) {
      c = 0;
      for (k = i; k <= j; k++) c = f[k] ^ c;
      ma = max(ma, c);
    }
  cout << ma;
  return 0;
}
