#include <bits/stdc++.h>
using namespace std;
const int N = 1000010;
int a[N];
int ans;

int main() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++)
    cin >> a[i];

  set<int> _set; // 哪个数字已经被淘汰掉了

  for (int i = 30; i >= 0; i--) {
    int cnt = 0; // 枚举每个数字的二进制数位,由高到低
    for (int j = 1; j <= n; j++) {
      if (a[j] >> i & 1 && !_set.count(j))
        cnt++;
    }
    if (cnt >= 2) {
      for (int j = 1; j <= n; j++)
        if (!(a[j] >> i & 1))
          _set.insert(j);
      ans = ans + (1 << i);
    }
  }
  cout << ans << endl;
  return 0;
}