#include <bits/stdc++.h>
using namespace std;
#define gok ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//#define endl "\n"
# define int long long
#define pb push_back
const int N = 3005,mod = 1e9 + 7;
 int n;
 int a[20];
 int help(int id,int orr,int xr)
 {
     if(id==n)
        return (xr^orr);
     int op1=1e12,op2=1e12;
     op1 = help(id+1,(orr|a[id]),xr);
     op2 = help(id+1,a[id],(xr^orr));
     return min(op1,op2);
 }
signed main(){
	gok


     cin>>n;

     for(int i=0;i<n;i++)
        cin>>a[i];

     cout<<help(0,0,0);

  return 0;
}













#include <bits/stdc++.h>
using namespace std;
// #define LOCAL // 提出時はコメントアウト
#define DEBUG_

typedef long long ll;
const double EPS = 1e-9;
const ll INF = ((1LL<<62)-(1LL<<31));
typedef vector<ll> vecl;
typedef pair<ll, ll> pairl;
template<typename T> using uset = unordered_set<T>;
template<typename T, typename U> using mapv = map<T,vector<U>>;
template<typename T, typename U> using umap = unordered_map<T,U>;

#define ALL(v) v.begin(), v.end()
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i, n) REP(i, 0, n)
#define sz(x) (ll)x.size()
ll llceil(ll a,ll b) { return (a+b-1)/b; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> vector<vector<T>> genarr(ll n, ll m, T init) { return vector<vector<T>>(n,vector<T>(m,init)); }

///// DEBUG
#define DUMPOUT cerr
#define repi(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
template<typename T>istream&operator>>(istream&is,vector<T>&vec){for(T&x:vec)is>>x;return is;}
template<typename T,typename U>ostream&operator<<(ostream&os,pair<T,U>&pair_var){os<<"("<<pair_var.first<<", "<<pair_var.second<<")";return os;}
template<typename T>ostream&operator<<(ostream&os,const vector<T>&vec){os<<"{";for(int i=0;i<vec.size();i++){os<<vec[i]<<(i+1==vec.size()?"":", ");}
os<<"}";return os;}
template<typename T,typename U>ostream&operator<<(ostream&os,map<T,U>&map_var){os<<"{";repi(itr,map_var){os<<*itr;itr++;if(itr!=map_var.end())os<<", ";itr--;}
os<<"}";return os;}
template<typename T>ostream&operator<<(ostream&os,set<T>&set_var){os<<"{";repi(itr,set_var){os<<*itr;itr++;if(itr!=set_var.end())os<<", ";itr--;}
os<<"}";return os;}
void dump_func(){DUMPOUT<<endl;}
template<class Head,class...Tail>void dump_func(Head&&head,Tail&&...tail){DUMPOUT<<head;if(sizeof...(Tail)>0){DUMPOUT<<", ";}
dump_func(std::move(tail)...);}
#ifndef LOCAL
#undef DEBUG_
#endif
#ifdef DEBUG_
#define DEB
#define dump(...)                                                          \
DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                            \
        << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]"        \
        << endl                                                            \
        << "    ",                                                         \
    dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif

//////////

#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

int solve(ostringstream &cout) {
    #ifdef LOCAL
    ifstream in("../../Atcoder/input.txt");
    cin.rdbuf(in.rdbuf());
    #endif

    ll N;
    cin>>N;

    ll ans = 0;
    vecl A(N);
    rep(i,N) cin>>A[i], ans ^= A[i]; 

    dump(ans);
    if (N == 1) {
        cout << ans << endl;
        return 0;
    }

    ll e = 0;
    // ll ans = INF;
    rep(i,1<<(N-1)) {
        if (i == 0) continue;
        ll s = 0;
        vecl OR;
        ll current = e;
        rep(j,N-1) {
            if (i & (1<<j)) { // i - i + 1
                current = current | A[j];
                OR.push_back(current);
                current = e;
                s = i + 1;
            } 
            else {
                current = current | A[j];
            }
        }

        OR.push_back(current | A[N-1]);
        
        ll sub = 0;
        for (auto x : OR) sub ^= x;
        dump(i,sub,OR);
        chmin(ans,sub);
    }

    cout << ans << endl;

    return 0;
}

int main() {
    ostringstream oss;
    int res = solve(oss);

    cout << oss.str();
    return res;
}
