using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using static Template;
using static System.Console;
using static System.Convert;
using static System.Math;
using Pi = Pair<int, int>;

class Solver
{
    public void Solve(Scanner sc)
    {
        int N;long K;
        sc.Make(out N, out K);
        var A = sc.ArrLong;
        Array.Sort(A);
        List<long> p = new List<long>(), m = new List<long>();
        long pl=0, mi=0, ze = 0;
        for(var i = 0; i < N; i++)
        {
            if (A[i] > 0) { p.Add(A[i]); pl++; }
            else if (A[i] < 0) { m.Add(A[i]); mi++; }
            else ze++;
        }
        long r, l;
        if (pl * mi < K) K -= pl * mi;
        else
        {
            p.Reverse();
            r = 0; l = -(long)1e18-100;
            while (r - l > 1)
            {
                var mid = (r + l) >> 1;
                var idx = 0;var ct = 0L;
                for(var i = p.Count-1; i>=0;i--)
                {
                    while (idx != m.Count && m[idx] * p[i] <= mid)
                        idx++;
                    ct += idx;
                }
                if (ct >= K) r = mid;
                else l=mid;
            }
            Fail(r);
        }
        if (ze * (N - ze)+ze*(ze-1)/2 < K) K -= ze * (N - ze)+ze*(ze-1)/2;
        else Fail(0);
        m.Reverse();
        for (var i = 0; i < m.Count; i++) m[i] = -m[i];
        r = (long)1e18 + 100; l = 0;
        while (r - l > 1)
        {
            var mid = (r + l) >> 1;
            var ct = 0L;
            var idx = 0;
            for(var i = p.Count-1; i>=0;i--)
            {
                while (idx != p.Count && p[i] * p[idx] <= mid) idx++;
                ct += Max(0,idx - i-1);
            }
            idx = 0;
            for (var i = m.Count - 1; i >= 0; i--)
            {
                while (idx != m.Count && m[i] * m[idx] <= mid) idx++;
                ct += Max(0, idx - i-1);
            }
            if (ct >= K) r = mid;
            else l = mid;
        }
        WriteLine(r);
    }
    #region UpperBound/LowerBound
    public static int UpperBound<T>(IList<T> array, T value, Comparison<T> cmp = null)
    {
        cmp = cmp ?? Comparer<T>.Default.Compare;
        var low = -1;
        var high = array.Count;
        while (high - low > 1)
        {
            var mid = (high + low) / 2;
            if (cmp(array[mid], value) == 1) high = mid;
            else low = mid;
        }
        return high;
    }

    public static int LowerBound<T>(IList<T> array, T value, Comparison<T> cmp = null)
    {
        cmp = cmp ?? Comparer<T>.Default.Compare;
        var low = -1;
        var high = array.Count;
        while (high - low > 1)
        {
            var mid = (high + low) / 2;
            if (cmp(array[mid], value) != -1) high = mid;
            else low = mid;
        }
        return high;
    }
    #endregion
}

#region Template
public static class Template
{
    static void Main(string[] args)
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver().Solve(new Scanner());
        Console.Out.Flush();
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) == 1) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) == -1) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(ref T a, ref T b) { var t = b; b = a; a = t; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T[] Create<T>(int n, Func<T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(); return rt; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T[] Create<T>(int n, Func<int, T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(i); return rt; }
    public static T[] Copy<T>(this T[] A) => Create(A.Length, i => A[i]);
    public static T Unify<T>(this T[] A, Func<T, T, T> f, T init = default(T)) { for (var i = 0; i < A.Length; i++) init = f(init, A[i]);return init; }
    public static void Fail<T>(T s) { Console.WriteLine(s); Console.Out.Close(); Environment.Exit(0); }
}

public class Scanner
{
    public string Str => Console.ReadLine().Trim();
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public int[] ArrInt => Str.Split(' ').Select(int.Parse).ToArray();
    public long[] ArrLong => Str.Split(' ').Select(long.Parse).ToArray();
    public char[][] Grid(int n) => Create(n, () => Str.ToCharArray());
    public int[] ArrInt1D(int n) => Create(n, () => Int);
    public long[] ArrLong1D(int n) => Create(n, () => Long);
    public int[][] ArrInt2D(int n) => Create(n, () => ArrInt);
    public long[][] ArrLong2D(int n) => Create(n, () => ArrLong);
    private Queue<string> q = new Queue<string>();
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T Next<T>() { if (q.Count == 0) foreach (var item in Str.Split(' ')) q.Enqueue(item); return (T)Convert.ChangeType(q.Dequeue(), typeof(T)); }
    public void Make<T1>(out T1 v1) => v1 = Next<T1>();
    public void Make<T1, T2>(out T1 v1, out T2 v2) { v1 = Next<T1>(); v2 = Next<T2>(); }
    public void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3) { Make(out v1, out v2); v3 = Next<T3>(); }
    public void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4) { Make(out v1, out v2, out v3); v4 = Next<T4>(); }
    public void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5) { Make(out v1, out v2, out v3, out v4); v5 = Next<T5>(); }
    public void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6) { Make(out v1, out v2, out v3, out v4, out v5); v6 = Next<T6>(); }
    //public (T1, T2) Make<T1, T2>() { Make(out T1 v1, out T2 v2); return (v1, v2); }
    //public (T1, T2, T3) Make<T1, T2, T3>() { Make(out T1 v1, out T2 v2, out T3 v3); return (v1, v2, v3); }
    //public (T1, T2, T3, T4) Make<T1, T2, T3, T4>() { Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4); return (v1, v2, v3, v4); }
}
public class Pair<T1, T2> : IComparable<Pair<T1, T2>>
{
    public T1 v1;
    public T2 v2;
    public Pair() { }
    public Pair(T1 v1, T2 v2)
    { this.v1 = v1; this.v2 = v2; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2> p)
    {
        var c = Comparer<T1>.Default.Compare(v1, p.v1);
        if (c == 0)
            c = Comparer<T2>.Default.Compare(v2, p.v2);
        return c;
    }
    public override string ToString() => $"{v1.ToString()} {v2.ToString()}";
    public void Deconstruct(out T1 a, out T2 b) { a = v1; b = v2; }
}

public class Pair<T1, T2, T3> : Pair<T1, T2>, IComparable<Pair<T1, T2, T3>>
{
    public T3 v3;
    public Pair() : base() { }
    public Pair(T1 v1, T2 v2, T3 v3) : base(v1, v2)
    { this.v3 = v3; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2, T3> p)
    {
        var c = base.CompareTo(p);
        if (c == 0)
            c = Comparer<T3>.Default.Compare(v3, p.v3);
        return c;
    }
    public override string ToString() => $"{base.ToString()} {v3.ToString()}";
    public void Deconstruct(out T1 a, out T2 b, out T3 c) { Deconstruct(out a, out b); c = v3; }
}
#endregion

Measured memory_bytes: 41544