#ifdef NACHIA
#define _GLIBCXX_DEBUG
#else
// disable assert
#define NDEBUG
#endif
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
using ll = long long;
const ll INF = 1ll << 60;
#define REP(i,n) for(ll i=0; i<ll(n); i++)
template <class T> using V = vector<T>;
template <class A, class B> void chmax(A& l, const B& r){ if(l < r) l = r; }
template <class A, class B> void chmin(A& l, const B& r){ if(r < l) l = r; }

void testcase(){
  ll N; cin >> N;
  V<ll> A(N); REP(i,N) cin >> A[i];
  ll orx = 0, andx = 0;
  for(ll j=29; j>=0; j--){
    (j%2 == 0 ? andx : orx) |= 1ll << j;
    ll cnt = 0;
    ll v = 0;
    for(auto a : A) if((a&andx) == andx){ v |= a; cnt++; }
    if((v&orx) != orx || cnt == 0){
      (j%2 == 0 ? andx : orx) -= 1ll << j;
    }
  }
  cout << (orx + andx) << "\n";
}

int main(){
  cin.tie(0)->sync_with_stdio(0);
  testcase();
  return 0;
}