#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i < (int)(n+1); i++)
#define repn(i,a,b) for (int i = (int)(a) ; i < (int)(b+1); i++)
#define repv(i, n) for (int i = (int)(n-1); i >= 0; i--)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define sz(x) ((int)(x).size())
#define cauto const auto&
#define bit(n) (1LL<<(n))
#define uni(v) v.erase( unique(v.begin(), v.end()), v.end() );
using ll = long long;
using P = pair<int,int>;
using PP = pair<int, P>;
using Graph = vector<vector<int>>;
using mint = modint998244353;
#ifdef LOCAL
    #include <debug.hpp>
    #define debug(...) debug::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
    #define debug(...) (static_cast<void>(0))
#endif

int shift(int x){
    return (x%2==0) ? x/2 : x/2+pow(2,15);
}

int main(){
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i,n) cin >> a[i];
    vector<vector<bool>> dp(2,vector<bool>(bit(16),false));
    int now = a[0];
    rep(i,16){
        dp[0][now] = true;
        now = shift(now);
    }
    rep(i,n-1){
        rep(j,bit(16)){
            if(dp[i%2][j]){
                now = a[(i+1)];
                rep(k,16){
                    dp[(i+1)%2][now|j] = true;
                    now = shift(now);
                }
            }
        }

    }
    int ans = 0;
    rep(i,bit(16)){
        if(n%2 == 0){
            if(dp[1][i]) ans = max(ans,i);
        } else {
            if(dp[0][i]) ans = max(ans,i);
        }
    }
    cout << ans << endl;
    return 0;
}