using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	static int[] c,d;
	static long cl,dl,ze;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.La;
		var a=sc.Ia;
		cl=0;
		ze=0;
		for(int i = 0;i<s[0];i++) {
			if(a[i]<0){cl++;}
			else if(a[i]==0){ze++;}
		}
		dl=s[0]-cl-ze;
		c=new int[cl];
		d=new int[dl];
		for(int i = 0,j=0,k=0;i<s[0];i++) {
			if(a[i]<0){
				c[j]=-a[i];
				j++;
			}
			else if(a[i]!=0){
				d[k]=a[i];
				k++;
			}
		}
		Array.Sort(c);
		Array.Sort(d);
		long lb=0,ub=long.MaxValue-1,mid=0;
		while(ub-lb>1){
			mid=(ub+lb)/2;
			if(Fu(mid)>=s[1]){ub=mid;}
			else{lb=mid;}
		}
		if(lb!=0){
			Console.WriteLine("{0}",lb);
			return;
		}
		lb=long.MinValue+2;ub=1;
		while(ub-lb>1){
			mid=(ub+lb)/2;
			if(Fu(mid)>=s[1]){ub=mid;}
			else{lb=mid;}
		}
		Console.WriteLine("{0}",lb);
	}
	static long Fu(long n){
		long p=0;
		if(n>0){
			p+=ze*(ze-1)/2+(ze*dl)+(ze*cl);
			p+=cl*dl;
			for(int i = 0;i<dl;i++) {
				long g=(n-1)/d[i];
				int z=d.Bs(g+1,true);
				if(i>=z){break;}
				p+=z-i;
			}
			for(int i = 0;i<cl;i++) {
				long g=(n-1)/c[i];
				int z=c.Bs(g+1,true);
				if(i>=z){break;}
				p+=z-i;
			}
		}
		else if(n<0){
			for(int i = (int)dl-1;i>=0;i--) {
				long g=-((n)/d[i]-1);
				int z=c.Bs(g,false);
				if(cl-z<=0){break;}
				p+=cl-z;
			}
		}
		else{
			p+=cl*dl;
		}
		return p;
	}
}
static class Ex1{
	public static int Bs(this int[] a,long x,bool b){return Bs2(a,x,b,a.Length);}
	public static int Bs(this int[] a,long x,bool b,int ub){return Bs2(a,x,b,ub+1);}
	private static int Bs2(int[] a,long x,bool b,int ub){
		int lb=-1,mid=0;
		while(ub-lb>1){
			mid=(ub+lb)/2;
			if(a[mid]>=x){ub=mid;}
			else{lb=mid;}
		}
		return b?lb:ub;
	}
}
public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),int.Parse);}
	public int[] Ia3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),long.Parse);}
	public long[] La3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),double.Parse);}
	public double[] Da3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}

Measured memory_bytes: 34908