#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001LL


int main(){
	int n;
	cin>>n;
	vector<int> a(n);
	rep(i,n){
		cin>>a[i];
	}
	int ans = 0;
	int mask = 0;
	for(int i=29;i>=0;i--){
		if(i%2==1){
			bool f = false;
			rep(j,a.size()){
				if((a[j]>>i)&1){
					f = true;
				}
			}
			if(f){
				mask |= 1<<i;
				ans += 1<<i;
			}
		}
		else{
			vector<int> b;
			rep(j,a.size()){
				if((a[j]>>i)&1){
					b.push_back(a[j]);
				}
			}
			if(b.size()==0)continue;
			int cur = 0;
			rep(j,b.size()){
				cur |= b[j];
			}
			if((mask & cur)!=mask)continue;
			ans += 1<<i;
			a = b;
		}
		
	}
	cout<<ans<<endl;
	return 0;
}