#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>
#include <locale>

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,K,A[200200];
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]);}
    }
    if(K<=pl.size()*mi.size()){
        //mid以下の数は何個あるかで二分探索小さいやつが左にあるとだんだん
        sort(pl.begin(),pl.end());
        sort(mi.begin(),mi.end());

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


        }
        cout<<ok<<endl;
        return 0;
    }
    K-=pl.size()*mi.size();
    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());
    sort(mi.begin(),mi.end(),greater<long long int>());

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


    }
    cout<<ok<<endl;

    
}

Measured memory_bytes: 3572