#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, mx = -(int)1E9;
  cin >> n;
  int *a = new int[n];
  for (int i = 0; i < (int)n; i++) cin >> a[i];
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < n + 1 - i; j++) {
      int h = 0;
      for (int k = j; k < j + i; k++) h ^= a[k];
      if (h > mx) mx = h;
    }
  }
  cout << mx << endl;
  return 0;
}
