#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;

#define For(i, a, n) for(ll i=a;i<n;i++)
#define vec vector
#define sz(x) (ll)x.size()
#define all(x) begin(x), end(x)

// template<class A, class B>

template<typename... Args>
void dbg(Args&&... args){
    ((cerr<<args<<" |"),...);
    cerr<<endl;
}

void solve(){

    ll n;
    cin >> n;
    vec<ll> a(n);
    for(ll i = 0; i < n; i++){
        cin >> a[i];
    }

    ll current_power = 1;
    ll sum_so_far = 0;
    ll result = 0;
    while(true){
        ll finished = 0;
        for(ll i = 0; i < n; i++){
            sum_so_far += current_power*(a[i]%2);
            a[i] /= 2;
            if(a[i] == 0){
                finished++;
            }
        }
        if(sum_so_far >= current_power){
            result += current_power;
        }else{
            if(finished == n){
                break;
            }
        }
        current_power *= 2;
    }
    cout << result << "\n";

}

int main(){
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    ll t = 1;//cin>>t;
    while(t--)solve();
}