// Goods things are coming, just keep believing 
 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace __gnu_pbds;
using namespace std;
 
 
#define FOR(i, x, n) for(ll i = x; i < n; i++) 
#define pb push_back
#define pf push_front
#define ll long long
#define hii cout << "hii" << endl
#define okay cout << "okay" << endl
// #define hey cout << "hey" << endl
#define pii pair<int, int>
#define pll pair<ll, ll>
#define mp make_pair
#define endl '\n'
#define ff first 
#define int long long
#define ss second
#define vi vector<int>
#define all(s) s.begin(), s.end()
#define si size()
 #define ld long double
#define INF 1000000000;
 
template <class T> ostream& operator << (ostream &os, const vector<T> &v) { for (T i : v) os << i << ' '; return os; }
template <class T> ostream& operator << (ostream &os, const set<T> &v) { for (T i : v) os << i << ' '; return os; }
template <class T, class S> ostream& operator << (ostream &os, const pair<T, S> &v) { os << v.first << ' ' << v.second; return os; }
template <class T, class S> ostream& operator << (ostream &os, const unordered_map<T, S> &v) { for (auto i : v) os << '(' << i.first << "=>" << i.second << ')' << ' '; return os; } 
 
 
 
#ifndef ONLINE_JUDGE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
    template <class Arg1> void __f(const char* name, Arg1&& arg1) { cerr << name << " : " << arg1 << endl; }
    template <class Arg1, class... Args>
    void __f(const char* names, Arg1&& arg1, Args&&... args) {
        const char* sep = strchr(names + 1, ',');
        cerr.write(names, sep - names) << " : " << arg1 << "  ";
        __f(sep + 1, args...);
    }
#else
#define trace(...) 0
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define _CRT_SECURE_NO_WARNINGS
#endif // ifndef ONLINE_JUDGE
 
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
 
 
 
const int N = 2e5 + 5;
const int LG = 20;
const int mod = 1e9 + 7;

int arr[N];
vector<int> pos;
vector<int> neg;
int ptr = 1;
int n, k;
int sp = -1;
int se = -1;

int cnt1(int m)
{
	int cnt = 0;
	for(int i = 0; i < n; i++)
	{
		if(arr[i] == 0)
		{
			if(0 <= m)
			{
				cnt += n - i - 1;
			}
			continue;
		}
		if(arr[i] < 0)
		{
			int s = i + 1;
			int e = se;
			int idx = -1;
			while(s <= e)
			{
				int mid = s + e >> 1;
				if(arr[i] * arr[mid] <= m)
				{
					idx = mid;
					e = mid - 1;
				}
				else
				{
					s = mid + 1;
				}
			}
			if(idx != -1)
			{
				cnt += se - idx + 1;
			}
			s = max(se + 1, i + 1);
			e = n - 1;
			idx = -1;
			while(s <= e)
			{
				int mid = s + e >> 1;
				if(arr[i] * arr[mid] <= m)
				{
					idx = mid;
					e = mid - 1;
				}
				else
				{
					s = mid + 1;
				}
			}
			if(idx != -1)
			{
				cnt += (n - 1) - idx + 1;
			}
		}
		else
		{
			int s = max(se + 1, i + 1);
			int e = n - 1;
			int idx = -1;
			while(s <= e)
			{
				int mid = s + e >> 1;
				if(arr[i] * arr[mid] <= m)
				{
					idx = mid;
					s = mid + 1;
				}
				else
				{
					e = mid - 1;
				}
			}
			if(idx != -1)
			{
				cnt += idx - max(se + 1, i + 1) + 1;
			}
		}
	}
	return cnt;
}

void solve()
{
	cin >> n >> k;
	for(int i = 0; i < n; i++)
	{
		cin >> arr[i];
		pos.push_back(arr[i]);
	}
	sort(arr, arr + n);
	for(int i = 0; i < n; i++)
	{
		if(arr[i] < 0)
		{
			se = i;
			if(sp == -1)
			{
				sp = i;
			}
		}
	}
	int s = -1e18;
	int e = 1e18;
	while(s <= e)
	{
		int mid = (s + e) / 2;
		if(cnt1(mid) >= k)
		{
			e = mid - 1;
		}
		else
		{
			s = mid + 1;
		}
	}
	// trace(cnt1(6));
	cout << e + 1 << endl;
}

int32_t main() 
{
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    int t;
    t = 1;
    // cin >> t;
    while(t--)
    	solve();
    return 0;
}

Measured memory_bytes: 3568