#include <vector>
#include <array>
#include <cstdio>

#define ull unsigned long long

using namespace std;

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

	array<ull, 64> arr;

	arr.fill(0);


	for (int i = 0; i < n; ++i) {
		ull v;
		scanf("%lld", &v);

		for (int i = 0; i < 64; ++i) {
			if ((v & 1) == 1) {
				arr[i] += 1;
			}
			v = v >> 1;
		}
	}

	ull possible = 0;

	for (int i = 0; i < 64; ++i) {
		if (arr[i] != 0) { possible |= 1 << i; }

		if (i == 63) break;

		arr[i+1] += arr[i] / 2;
	}


	printf("%lld\n", possible);
}