#include <bits/stdc++.h>
int N, ar[1000000];
int main() {
  int max = -1;
  scanf("%d", &N);
  for (int i = 0; i < N; i++) scanf("%d", &ar[i]);
  for (int i = 0; i < N; i++)
    for (int j = i; j < N; j++) {
      int T = 0;
      for (int k = i; k <= j; k++) T ^= ar[k];
      if (T > max) max = T;
    }
  printf("%d\n", max);
  return 0;
}
