using Complib.Generic;
using CompLib.Util;
using System;
using System.Collections.Generic;

public class Program
{
    long N;
    long K;
    long[] A;
    List<long> plus, minus;
    public void Solve()
    {
        var sc = new Scanner();
        N = sc.NextInt();
        K = sc.NextLong();
        A = sc.LongArray();

        plus = new List<long>();
        minus = new List<long>();

        foreach (var i in A)
        {
            if (i >= 0) plus.Add(i);
            else minus.Add(i);
        }

        plus.Sort();
        minus.Sort((a, b) => -a.CompareTo(b));
        // にぶたん
        // med以下がk個以下

        long ng = long.MinValue / 2;
        long ok = long.MaxValue / 2;

        while (ok - ng > 1)
        {
            long med = (ok + ng) / 2;
            if (C(med))
            {
                ok = med;
            }
            else
            {
                ng = med;

            }
        }

        Console.WriteLine(ok);
    }

    // n以下がk個以下か
    bool C(long n)
    {
        long cnt = 0;
        if (n >= 0)
        {
            cnt += (long)plus.Count * minus.Count;

            for (int i = 0; i < plus.Count; i++)
            {
                int ok = -1;
                int ng = i;
                while (ng - ok > 1)
                {
                    int med = (ok + ng) / 2;
                    if ((long)plus[i] * plus[med] <= n)
                    {
                        ok = med;
                    }
                    else
                    {
                        ng = med;
                    }
                }

                cnt += ng;
            }

            for (int i = 0; i < minus.Count; i++)
            {
                int ok = -1;
                int ng = i;
                while (ng - ok > 1)
                {
                    int med = (ok + ng) / 2;
                    if ((long)minus[i] * minus[med] <= n)
                    {
                        ok = med;
                    }
                    else
                    {
                        ng = med;
                    }
                }

                cnt += ng;
            }
        }
        else
        {
            for (int i = 0; i < plus.Count; i++)
            {
                int ng = -1;
                int ok = minus.Count;

                while (ok - ng > 1)
                {
                    int med = (ok + ng) / 2;

                    if ((long)plus[i] * minus[med] <= n)
                    {
                        ok = med;
                    }
                    else
                    {
                        ng = med;
                    }
                }

                cnt += minus.Count - ok;
            }
        }

        return cnt >= K;
    }

    public static void Main(string[] args) => new Program().Solve();
}


namespace Complib.Generic
{
    using System.Collections.Generic;
    class HashMap<K, V> : Dictionary<K, V>
    {
        public V this[K key]
        {
            set { base[key] = value; }
            get
            {
                V o;
                return TryGetValue(key, out o) ? o : base[key] = default(V);
            }
        }
    }
}

namespace CompLib.Util
{
    using System;
    using System.Linq;
    class Scanner
    {
        private int _index;
        private string[] _line;
        const char separator = ' ';

        public Scanner()
        {
            _index = 0;
            _line = new string[0];
        }

        public string Next()
        {
            while (_index >= _line.Length)
            {
                _line = Console.ReadLine().Split(separator);
                _index = 0;
            }
            return _line[_index++];
        }
        public int NextInt() => int.Parse(Next());
        public long NextLong() => long.Parse(Next());
        public double NextDouble() => double.Parse(Next());
        public char NextChar() => Next()[0];
        public char[] NextCharArray() => Next().ToCharArray();

        public string[] Array()
        {
            _line = Console.ReadLine().Split(separator);
            _index = _line.Length;
            return _line;
        }
        public int[] IntArray() => Array().Select(int.Parse).ToArray();
        public long[] LongArray() => Array().Select(long.Parse).ToArray();
        public double[] DoubleArray() => Array().Select(double.Parse).ToArray();
    }
}


Measured memory_bytes: 47136