/**
 *    author:  otera    
**/
#include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<deque>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
using namespace std;

#define int long long
typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const int inf=1e9+7;
const ll INF=1LL<<61 ;
const ll mod=1e9+7 ;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define pb push_back
#define debug(x)  cerr << #x << " = " << (x) << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

void solve() {
	int n, k; cin >> n >> k;
    vector<int> a(n);
    int mcnt = 0, pcnt = 0, zcnt = 0;
    vector<int> p, m, mm;
    rep(i, n) {
        cin >> a[i];
        if(a[i] < 0) {
            ++mcnt;
            m.pb(a[i]);
            mm.pb(-a[i]);
        }
        else if(a[i] == 0) ++zcnt;
        else {
            p.pb(a[i]);
            ++pcnt;
        }
    }
    sort(all(a));
    sort(all(m));
    sort(all(mm));
    sort(all(p));
    int ng = -INF, ok = INF;
    while(ok - ng > 1) {
        int mid = (ok + ng) / 2;
        int cnt = 0;
        rep(i, n) {
            if(a[i] == 0) {
                if(mid >= 0) cnt += n;
                else cnt += 0;
            } else if(a[i] > 0) {
                if(mid > 0) {
                    cnt += upper_bound(all(p), mid / a[i]) - p.begin() + mcnt + zcnt;// - (a[i] * a[i] <= mid ? 1: 0);
                } else if(mid == 0) {
                    cnt += mcnt + zcnt;
                } else {
                    cnt += mm.end() - lower_bound(all(mm), (-mid + a[i] - 1) / a[i]);
                }
            } else { //a[i] < 0
                if(mid > 0) {
                    cnt += pcnt + zcnt + upper_bound(all(mm), mid / (-a[i])) - mm.begin();// - (a[i] * a[i] <= mid ? 1: 0);
                } else if(mid == 0) {
                    cnt += pcnt + zcnt;
                } else if(mid < 0) {
                    cnt += p.end() - lower_bound(all(p), (-mid - a[i] - 1) / (-a[i]));
                }
            }

            if(a[i] * a[i] <= mid) --cnt;
            //if(mid == 8) cerr << cnt << endl;
        }
        //cerr << mid << " " << cnt / 2 << endl;
        if(cnt / 2 >= k) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    cout << ok << endl;
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(10);
	//int t; cin >> t; rep(i, t)solve();
	solve();
    return 0;
}

Measured memory_bytes: 5100