#include <bits/stdc++.h>
using namespace std;

#define LSOne(S) ((S) & -(S))

int main() {

    int n;
    scanf("%d", &n);

    vector<long long> nums(n);

    vector<int> occ(70, 0); 

    for (int i = 0; i < n; i++) {
        scanf("%ld", &nums[i]);

        long long mm = nums[i];
        while (mm != 0) {
            long long r = LSOne(mm);
            int c = __builtin_ctz(r);
            occ[c]++;
            mm -= r;
        }
    }

    for (int i = 0; i < occ.size() - 1; ++i) {
        if (occ[i] >= 2) occ[i+1]++;
    }

    long long ans = 0;

    for (int i = 0; i < occ.size() - 1; ++i) if (occ[i] > 0) {
        ans |= 1 << i;
    }

    printf("%ld\n", ans);



    return 0;
}