using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace AtCorder
{
	public class Program
	{
		static void Main(string[] args)
		{
			var nk = Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
			long n = nk[0];
			long k = nk[1];
			long[] a = Console.ReadLine().Split(' ').Select(long.Parse).ToArray();

			Array.Sort(a);

			long ok = (long)(-1e18) - 1;
			long ng = (long)(1e18) + 1;
			while (ng - ok > 1) {
				long mid = (ng + ok) / 2;
				long cnt = 0;
				for (int i = 0; i < n; i++) {
					if (a[i] < 0) {
						cnt += n - LowerBoundIntR(i, a.Length, midd => a[i] * a[midd] < mid);
					} else {
						cnt += LowerBoundIntL(i, a.Length, midd => a[i] * a[midd] < mid) - i;
					}
				}

				if (cnt < k) {
					ok = mid;
				} else {
					ng = mid;
				}
			}

			Console.WriteLine(ok);
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static int LowerBoundIntR(int ng, int ok, Func<int, bool> check)
		{
			while (ok - ng > 1) {
				int mid = (ok + ng) / 2;
				if (check(mid)) {
					ok = mid;
				} else {
					ng = mid;
				}
			}

			return ok;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static int LowerBoundIntL(int ok, int ng, Func<int, bool> check)
		{
			while (ng - ok > 1) {
				int mid = (ok + ng) / 2;
				if (check(mid)) {
					ok = mid;
				} else {
					ng = mid;
				}
			}

			return ok;
		}
	}

	public class Scanner2
	{
		private readonly char[] delimiter_ = new char[] { ' ' };
		private readonly string filePath_;
		private readonly Func<string> reader_;
		private string[] buf_;
		private int index_;

		public Scanner2(string file = "")
		{
			if (string.IsNullOrWhiteSpace(file)) {
				reader_ = Console.ReadLine;
			} else {
				filePath_ = file;
				var fs = new StreamReader(file);
				reader_ = fs.ReadLine;
			}
			buf_ = new string[0];
			index_ = 0;
		}

		public string Next()
		{
			if (index_ < buf_.Length) {
				return buf_[index_++];
			}

			string st = reader_();
			while (st == "") {
				st = reader_();
			}

			buf_ = st.Split(delimiter_, StringSplitOptions.RemoveEmptyEntries);
			if (buf_.Length == 0) {
				return Next();
			}

			index_ = 0;
			return buf_[index_++];
		}

		public int Int() => int.Parse(Next());
		public long Long() => long.Parse(Next());
		public double Double() => double.Parse(Next());

		public int[] ArrayInt(int N, int add = 0)
		{
			int[] Array = new int[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Int() + add;
			}
			return Array;
		}

		public long[] ArrayLong(int N, long add = 0)
		{
			long[] Array = new long[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Long() + add;
			}
			return Array;
		}

		public double[] ArrayDouble(int N, double add = 0)
		{
			double[] Array = new double[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Double() + add;
			}
			return Array;
		}

		public void Save(string text)
		{
			if (string.IsNullOrWhiteSpace(filePath_)) {
				return;
			}

			File.WriteAllText(filePath_ + "_output.txt", text);
		}
	}
}

Measured memory_bytes: 40032