#include <bits/stdc++.h>
#include <atcoder/modint.hpp>
using namespace std;
 
using i32 = int;
using i64 = long long;
using i128 = __int128_t;
using f64 = double;
using p2 = pair<i64, i64>;
using p3 = tuple<i64, i64, i64>;
using mint = atcoder::modint998244353;
constexpr i64 inf = 1e18;
 
void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(18);
  _main();
}

void _main() {
  i64 n;
  cin >> n;
  vector<i64> a(n);
  for (i64 i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<i64> cnt(30, 0);
  vector<bool> ok(n, true);
  vector<vector<i64>> g(n);
  i64 ans = 0;
  for (i64 k = cnt.size() - 1; k >= 0; k--) {
    if (k % 2 == 1) {
      for (i64 i = 0; i < n; i++) {
        if (!ok[i]) continue;
        if (a[i] >> k & 1) {
          cnt[k]++;
          g[i].push_back(k);
        }
      }
      if (cnt[k] > 0) ans |= 1 << k;
    } else {
      vector<i64> ncnt = cnt;
      bool f = false;
      for (i64 i = 0; i < n; i++) {
        if (!ok[i]) continue;
        if (a[i] >> k & 1) {
          f = true;
          continue;
        }
        for (i64 x : g[i]) ncnt[x]--;
      }
      for (i64 i = 0; i < cnt.size(); i++) if (cnt[i] > 0 && ncnt[i] == 0) f = false;
      if (!f) continue;
      for (i64 i = 0; i < n; i++) {
        if (!ok[i]) continue;
        if (a[i] >> k & 1) continue;
        ok[i] = false;
        for (i64 x : g[i]) cnt[x]--;
      }
      ans |= 1 << k;
    }
  }
  cout << ans << "\n";
}