#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>

int main()
{
	long long n, k;
	scanf("%lld%lld", &n, &k);
	long long a[200000];
	for (long long i = 0; i < n; ++i)
	{
		scanf("%lld", a + i);
	}
	std::sort(a, a + n);
	long long l = -1000000000000000001;
	long long r = 1000000000000000001;
	while (r - l > 1)
	{
		long long mid = l + (r - l) / 2;
		long long cnt = 0;
		for (long long i = 0; i < n - 1; ++i)
		{
			long long search;
			if (a[i] < 0)
			{
				search = mid <= 0 ? (-mid + (-a[i] - 1)) / (-a[i]) : mid / a[i];
				cnt += (a + n) - std::lower_bound(a + i + 1, a + n, search);
			}
			else if (a[i] == 0)
			{
				if (mid >= 0) cnt += n - (i + 1);
			}
			else
			{
				search = mid <= 0 ? (mid - (a[i] - 1)) / a[i] : mid / a[i];
				cnt += std::upper_bound(a + i + 1, a + n, search) - (a + i + 1);
			}
		}
		if (cnt >= k)
		{
			r = mid;
		}
		else
		{
			l = mid;
		}
	}
	printf("%lld\n", r);
}
