#include <bits/stdc++.h>

using namespace std;


long long count_set_bits(vector<long long> & a, int n){
    long long r = 0;
    for (const auto & i: a){
        r += (i & (1 << n)) >> n;
    }
    return r;
}


signed main(){
    int n;
    cin >> n;
    vector<long long> a(n);
    for (int i = 0; i < n; ++i){
        cin >> a[i];
    }
    vector<long long> dp(64);
    dp[0] = count_set_bits(a, 0);
    long long res = 0;
    if (dp[0]) res = 1;
    for (int i = 1; i <= 64; ++i){
        dp[i] = dp[i-1] / 2 + count_set_bits(a, i);
        res |= ((dp[i] ? 1 : 0) << i);
    }
    cout << res << endl;
}