#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
istream& operator>>(istream& in, pair<T1, T2>& a) {
  in >> a.first >> a.second;
  return in;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& out, pair<T1, T2> a) {
  out << a.first << " " << a.second;
  return out;
}
template <typename T, typename T1>
T maxs(T& a, T1 b) {
  if (b > a) a = b;
  return a;
}
template <typename T, typename T1>
T mins(T& a, T1 b) {
  if (b < a) a = b;
  return a;
}
const long long N = (1 << 21);
const long long M = N - 1;
pair<long long, long long> dp[N];
long long solve() {
  long long n;
  cin >> n;
  vector<long long> a(n + 1);
  auto add = [&](long long mask, long long j) {
    if (dp[mask].first == -1)
      dp[mask].first = j;
    else if (dp[mask].second == -1) {
      dp[mask].second = j;
      if (dp[mask].second < dp[mask].first)
        swap(dp[mask].first, dp[mask].second);
    } else if (dp[mask].second < j) {
      dp[mask].first = dp[mask].second;
      dp[mask].second = j;
    } else if (dp[mask].first < j && j != dp[mask].second) {
      dp[mask].first = j;
    }
  };
  for (long long i = 1; i < n + 1; i++) {
    cin >> a[i];
    add(a[i], i);
  }
  for (long long i = 0; i < 21; i++) {
    for (long long mask = 0; mask < N; mask++) {
      if ((mask) & (1 << i)) {
        if (dp[mask].first != -1) add(mask ^ (1 << i), dp[mask].first);
        if (dp[mask].second != -1) add(mask ^ (1 << i), dp[mask].second);
      }
    }
  }
  long long ans = 0;
  for (long long i = 1; i < n + 1; i++) {
    long long rev_mask = M - a[i];
    long long best = 0;
    for (long long j = 20; j >= 0; j--) {
      if (rev_mask & (1 << j)) {
        if (dp[best ^ (1 << j)].second != -1 && dp[best ^ (1 << j)].first > i) {
          best ^= (1 << j);
        }
      }
    }
    if (i + 2 <= n) maxs(ans, a[i] + best);
  }
  cout << ans << "\n";
  return 0;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
