#include <stdio.h>

int main()
{
	int i, j, N;
	long long A, X = 0;
	scanf("%d", &N);
	for (i = 1; i <= N; i++) {
		scanf("%lld", &A);
		X |= A;
	}
	for (A = 1; (A & X) != 0; A <<= 1);
	printf("%lld\n", A);
	fflush(stdout);
	return 0;
}