#include <bits/stdc++.h>

#define rep(i,a,b) for(int i = a; i < (b); ++i)
#define sz(x) (int)(x).size()

using namespace std;

using ll = long long;
using ull = unsigned long long;
using pi = pair<int, int>;
using vi = vector<int>;

void solve() {
	int n;
	cin >> n;
	vector<ull> sp(n);
	for(int i = 0; i < n; ++i) {
		cin >> sp[i];
	}
	ull res = 0;
	for(int i = 0; i < 64; ++i) {
		ull bit = (1ull << i);
		ull bm = bit - 1;
		for(int j = 0; j < n; ++j) {
			if(sp[j] & bit) {
				res |= bit;
				break;
			}
		}
		if(res & bit) continue;
		ull sm = 0;
		for(int j = 0; j < n; ++j) {
			sm += (sp[j] & bm);
			if(sm & bit) {
				res |= bit;
				break;
			}
		}
	}
	cout << res << '\n';

}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	solve();
}