#include <bits/stdc++.h>
using namespace std;
///////////////////////////////////////////
const long long int INF = 1LL<<60;
const long long int Mod = 1000000007;
using ll = long long int; using ci = const int;
using vi = vector<int>;  using Vi = vector<long long int>;
using P = pair<int, int>;  using PLL = pair<ll, ll>;
using matrix = vector<vector<ll>>;
#define pb(x) push_back(x)
#define mp(x,y) make_pair(x,y)
#define all(x) (x).begin(),(x).end()
#define rp(i,N) for(ll i = 0; i < (ll)N; i++)
#define repi(i,a,b) for(ll i = ll(a); i < ll(b); ++i)
template<class T>bool chmax(T &former, const T &b) { if (former<b) { former=b; return true; } return false; }
template<class T>bool chmin(T &former, const T &b) { if (b<former) { former=b; return true; } return false; }
template<class T>T sqar(T x){ return x*x; }//sqrt(x)は平方根;
#define Sort(v) std::sort(v.begin(), v.end(), std::greater<decltype(v[0])>()) //降順でVをソート
#define p_queue(v) priority_queue<v, vector<v>, greater<v> >
template<class T> inline void princ(T x){cout<<x<<" ";}; 
template<class T> inline void print(T x){cout<<x<<"\n";};
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
///////////////////////////////////////////////////////////////////////////////////

void solve(){
    ll n,k;
    cin >> n >> k;
    Vi a(n);
    ll m=0,z=0,p=0;
    rp(i,n){
        cin >> a.at(i);
        if(a.at(i)>0) p++;
        else if(a.at(i)==0) z++;
        else m++;
    }
    sort(all(a));
    if(k<=m*p){
        ll mid, ok = -1000000000000000001ll, ng = 0;
        while(abs(ok-ng)>1){
            mid = (ok+ng)/2;
            ll ctr=0;
            for(ll i=0; i<m;i++){
                ll Mid, Ok = n, Ng = m+z-1;
                while(abs(Ok-Ng)>1){
                    Mid = (Ok+Ng)/2;
                    if(a.at(i)*a.at(Mid)<mid)Ok = Mid;
                    else Ng = Mid;
                }//midではなくokを使わないとバグる!
                ctr += n-Ok;
            }
            if(ctr<k) ok = mid;
            else ng = mid;
        }//midではなくokを使わないとバグる!
        print(ok);
        return;
    }else if(k<=m*p+z*(m+p)+z*(z-1)/2){
        print(0);
        return;
    }else{
        k-=m*p+z*(m+p)+z*(z-1)/2;
        ll mid, ok = 0, ng = 1000000000000000001ll;
        while(abs(ok-ng)>1){
            mid = (ok+ng)/2;
            ll ctr=0;
            for(ll i=0; i<m; i++){
                ll Mid, Ok = m, Ng = -1;
                while(abs(Ok-Ng)>1){
                    Mid = (Ok+Ng)/2;
                    if(a[i]*a[Mid]<mid)Ok = Mid;
                    else Ng = Mid;
                }//midではなくokを使わないとバグる!
                if(Ok<=i)ctr+=m-i-1;
                else ctr+=m-Ok;
            }
            for(ll i=m+z; i<n; i++){
                ll Mid, Ok = m+z-1, Ng = n;
                while(abs(Ok-Ng)>1){
                    Mid = (Ok+Ng)/2;
                    if(a[i]*a[Mid]<mid)Ok = Mid;
                    else Ng = Mid;
                }//midではなくokを使わないとバグる!
                if(Ok>=i) ctr+=i-(m+z);
                else ctr+=Ok-(m+z-1);
            }
            if(ctr<k)ok = mid;
            else ng = mid;
        }//midではなくokを使わないとバグる!
        print(ok);
    }
    return;
}
int main(){
    cin.tie(0);ios::sync_with_stdio(false);
    std::cout<<std::fixed<<std::setprecision(30);
    solve();
    return 0;
}

Measured memory_bytes: 1792