// #define _GLIBCXX_DEBUG 
#include<bits/stdc++.h>
using namespace std;

using uint = unsigned int;
using ll = long long;

#define CIN( LL , A ) LL A; cin >> A 
#define GETLINE( A ) string A; getline( cin , A ) 
#define GETLINE_SEPARATE( A , SEPARATOR ) string A; getline( cin , A , SEPARATOR ) 
#define UNTIE ios_base::sync_with_stdio( false ); cin.tie( nullptr ) 
#define FOR( VAR , INITIAL , FINAL_PLUS_ONE ) for( ll VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ ) 
#define FOR_ITR( ARRAY , ITR , END ) for( auto ITR = ARRAY .begin() , END = ARRAY .end() ; ITR != END ; ITR ++ ) 
#define REPEAT( HOW_MANY_TIMES ) FOR( VARIABLE_FOR_REPEAT , 0 , HOW_MANY_TIMES ) 
#define RETURN( ANSWER ) cout << ( ANSWER ) << "\n"; return 0 
#define DOUBLE( PRECISION , ANSWER ) cout << fixed << setprecision( PRECISION ) << ( ANSWER ) << "\n"; return 0 
#define MIN( A , B ) A < B ? A : B;
#define MAX( A , B ) A < B ? B : A;

template <typename T> inline T Absolute( const T& a ){ return a > 0 ? a : - a; }

int main()
{
  UNTIE;
  CIN( ll , N );
  constexpr const ll power = 65536;
  constexpr const ll digit = 16;
  if( N >= digit ){
    RETURN( power - 1 );
  }
  constexpr const ll shift = power / 2;
  ll Ai;
  bool c[power] = {};
  ll answer[2][power];
  answer[0][0] = 0;
  ll size[2] = { 1 , 0 };
  ll signature_last = 0;
  ll signature_new = 1;
  ll value;
  N--;
  REPEAT( N ){
    cin >> Ai;
    ll ( &answer_last )[power] = answer[signature_last];
    ll& size_last = size[signature_last];
    ll ( &answer_new )[power] = answer[signature_new];
    ll& size_new = size[signature_new];
    size_new = 0;
    REPEAT( digit ){
      FOR( j , 0 , size_last ){
	value = answer_last[j] | Ai;
	if( ! c[value] ){
	  c[value] = true;
	  answer_new[size_new] = value;
	  size_new++;
	}
      }
      Ai = shift * ( Ai % 2 ) + Ai / 2;
    }
    if( size_new == 0 ){
      RETURN( power - 1 );
    }
    swap( signature_last , signature_new );
  }
  ll max = -1;
  {
    cin >> Ai;
    ll ( &answer_last )[power] = answer[signature_last];
    ll& size_last = size[signature_last];
    REPEAT( digit ){
      FOR( j , 0 , size_last ){
	value = answer_last[j] | Ai;
	if( ! c[value] ){
	  c[value] = true;
	  if( max < value ){
	    max = value;
	  }
	}
      }
      Ai = shift * ( Ai % 2 ) + Ai / 2;
    }
    if( max == -1 ){
      RETURN( power - 1 );
    }
  }
  RETURN( max );
}