/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <iostream>
#include <fstream>

#include <bits/stdc++.h>
#define ttt cout << "test ok" << endl;
#define sp << " " <<
using namespace std;
typedef long long ll;
const ll mod = ll(1e9+7);
const ll inf = ll(5e18);
template<typename T1, typename T2> ll ceill(T1 a, T2 b){ return (a+b-1)/b; }
void ans(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void ans2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){ fill((T*)array, (T*)(array+N), val); }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <vector>
#include <map>
using namespace std;

class debug
{
public:
    typedef long long ll;
    template<typename T> void vd(vector<T> vec);
    template<typename T> void vd2(vector<vector<T>> vec);
    template<typename T> void ad(T *arr, ll n);
    template<typename T, size_t N> void ad2(T (&arr)[N], ll n);
    template<typename T> void md(T mp);
};

#endif //INCLUDE_DEBUG_HPP

template<typename T> void debug::vd(vector<T> vec)
{
    for(auto vv : vec) cout << vv << " ";
    cout << endl;
}

template<typename T> void debug::vd2(vector<vector<T>> vec)
{
    for(auto vv : vec) for(auto vvv : vv) cout << vvv << " ";
    cout << endl;
}

template<typename T> void debug::ad(T *arr, ll n)
{
    for(int i=0; i<=n; i++) cout << arr[i] << " ";
    cout << endl;
}

template<typename T, size_t N> void debug::ad2(T (&arr)[N], ll n)
{
    for(int i=0; i<=N; i++) for(int j=0; j<=n; j++) cout << arr[i][j] << " ";
    cout << endl;
}

template<typename T> void debug::md(T mp)
{
    cout << "key : value" << endl;
    for(auto const& m : mp) cout << m.first << " : " << m.second << endl;
    cout << endl;
}
debug debug;

class DPairs {
public:
	void solve(std::istream& in, std::ostream& out)
	{
	    ll n, k;
	    in >> n >> k;
	    vector<ll> a(n);
	    for(int i=0; i<n; i++){
	        in >> a[i];
	    }

	    sort(a.begin(), a.end());

	    ll inf_buf = ll(1e18)+1;
	    ll l = -inf_buf, r = inf_buf;
	    while(l+1 < r){
	        ll x = (l+r) / 2;

	        bool ok;
	        ll pos = 0;
	        for(int i=0; i<n; i++) {
                if (a[i] < 0) {
                    ll l = -1, r = n;
                    while (l + 1 < r) {
                        ll cur = (l + r) / 2;
                        if(a[cur]*a[i] < x) r = cur;
                        else l = cur;
                    }
                    pos += n-r;
                } else {
                    ll l = -1, r = n;
                    while(l + 1 < r) {
                        ll cur = (l+r) / 2;
                        if(a[cur]*a[i] < x) l = cur;
                        else r = cur;
                    }
                    pos += r;
                }
                if(a[i] * a[i] < x) pos--;
            }
	        pos /= 2;

	        if(pos < k) l = x;
	        else r = x;
	    }

	    out << l << endl;
	}
};


int main() {
	DPairs solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 1792