#include <bits/stdc++.h>
using namespace std;
int n, a[111], dp[111][111], maxx;
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  for (int i = 1; i <= n; i++) maxx = max(maxx, a[i]);
  for (int len = 2; len <= n; len++)
    for (int j = 1; j <= n - len + 1; j++) {
      int o = 0;
      for (int h = j; h <= j + len - 1; h++) o ^= a[h];
      if (o > maxx) maxx = o;
    }
  cout << maxx;
  return 0;
}
