#include <algorithm>
#include <complex>
#include <cstdlib>
#include <ctime>
#include <time.h>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <numeric>
#include <limits>
#include <type_traits>


using namespace std;
#define SAY_YES cout << "YES" << endl;
#define SAY_Yes cout << "Yes" << endl;
#define SAY_NO cout << "NO" << endl;
#define SAY_No cout << "No" << endl;
#define IFYES(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "YES" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "NO" << endl;  \
    }
#define IFYes(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "Yes" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "No" << endl;  \
    }
#define IFyes(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "yes" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "no" << endl;  \
    }
#define DEBUG_OUTPUT_ARRAY(XXX, ONE)                            \
    for (int i = 0; i < (ONE); i++)                             \
    {                                                           \
        cout << "DEBUG: i = " << i << " -> " << XXX[i] << endl; \
    }
#define DEBUG_OUTPUT_ARRAY2(XXX, ONE, TWO)                             \
    for (int i = 0; i < (ONE); i++)                                    \
    {                                                                  \
        cout << "<<< i = " << i << " >>>" << endl;                     \
        for (int j = 0; j < (TWO); j++)                                \
        {                                                              \
            cout << "DEBUG: j = " << j << " -> " << XXX[i][j] << endl; \
        }                                                              \
    }
#define DEBUG_OUTPUT_ARRAY2_BOX(XXX, ONE, TWO) \
    for (int i = 0; i < (ONE); i++)            \
    {                                          \
        cout << i << "  ";                     \
        for (int j = 0; j < (TWO); j++)        \
        {                                      \
            cout << XXX[i][j] << " ";          \
        }                                      \
        cout << endl;                          \
    }

typedef pair<long long int, long long int> pll;


const long long int mod = 1000000007;
const long long int INF = 1e18;
const long double PI=3.14159265358979323; 

long long int N,M,K,A[200300]={},B,c[200],res=0,Match[20]={0,2,5,5,4,5,6,3,7,6};

vector<long long int>pl,mi;
int main()
{
    cout << fixed << setprecision(18);
    cin>>N>>K;
    for(long long int i = 0; i < N; i++){
        cin>>A[i];
        if(A[i]>0){pl.push_back(A[i]);}
        else if(A[i]<0){mi.push_back(A[i]);}
    }
    //cout<<pl.size()<<" "<<mi.size()<<" "<<pl.size()*mi.size()<<" "<<K<<endl;
    if(K<=pl.size()*mi.size()){
        sort(pl.begin(),pl.end());
        sort(mi.begin(),mi.end());
        long long int ng=-INF-1,ok=0,mid,r=0;
        while(ok-ng>1){
            long long int tmp=0;
            r=0;
            mid=(ok+ng)/2;
            for(long long int i = 0; i < pl.size(); i++){
                while(r!=mi.size()&&mi[r]*pl[i]<=mid){
                    r++;
                }
                tmp+=r;
                //if(i==0)cout<<r<<endl;
            }
            //cout<<r<<" "<<tmp<<" "<<mid<<endl;
            if(tmp<K){
                ng=mid;
            }else{
                ok=mid;
            }
        }
        cout<<ok<<endl;
        return 0;
    }
    K-=pl.size()*mi.size();
    //cout<<K<<endl;
    long long int zero=N-pl.size()-mi.size();
    if(K<=zero*(pl.size()+mi.size())+zero*(zero-1)/2){
        cout<<0<<endl;
        return 0;
    }

    K-=zero*(pl.size()+mi.size())+zero*(zero-1)/2;
    
        sort(pl.begin(),pl.end(),greater<long long int>());
        sort(mi.begin(),mi.end());
        long long int ng=0,ok=INF+1,mid,r=0,r2=0;
        while(ok-ng>1){
            long long int tmp=0,tmp2=0;
            r=pl.size();
            r2=mi.size();
            mid=(ok+ng)/2;
            for(long long int i = 0; i < pl.size(); i++){
                while(r!=0&&pl[r-1]*pl[i]<=mid){
                    r--;
                }
                tmp+=pl.size()-r;
                if(i>=r){tmp--;}
            }

            for(long long int i = 0; i < mi.size(); i++){
                while(r2!=0&&mi[r2-1]*mi[i]<=mid){
                    r2--;
                }
                tmp2+=mi.size()-r2;
                if(i>=r2){tmp2--;}
            }
            tmp=tmp/2+tmp2/2;
            if(tmp<K){
                ng=mid;
            }else{
                ok=mid;
            }
        }
    cout<<ok<<endl;
    return 0;
        
    

}    


Measured memory_bytes: 3572