#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define rep(i,a,b) for(int i =a; i <(b); ++i)

const int BIT = 62;

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

    int n;
    cin >> n;
    vector<ll> a(n);
    for (auto &x : a) cin >> x;
    vector<int> cnt(BIT + 1, 0);
    for (int i = 0; i < n; i++) {
        for (int j = 0; a[i] > 0; j++) {
            if (a[i] % 2 == 1) cnt[j] += 1;
            a[i] /= 2;
        }
    }
    ll ans = 0;
    for (int i = 0; i <= BIT; i++) {
        if (cnt[i] != 0) {
            ans |= (1ll << i);
        }
        if (cnt[i] < 2) continue;
        cnt[i + 1] += cnt[i] / 2;
    }
    cout << ans << "\n";
    return 0;
}