#include <cassert>
#include <algorithm>
#include <array>
#include <bitset>
#include <cctype>
#include <cstdint>
#include <cmath>
#include <complex>
#include <chrono>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>
#include <random>
#include <memory>
#include <utility>
#include <limits>
#include "limits.h"
 
#define rep(i, a, b) for (long long (i) = (a); (i) < (b); (i)++)
#define all(i) i.begin(), i.end()
#define debug(...) std::cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)

void debug_out(){std::cerr<<std::endl;}

template<typename Head,typename... Tail>
void debug_out(Head h,Tail... t){
  std::cerr<<" "<<h;
  debug_out(t...);
}
 
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, std::pair<T1, T2> pa) {
  return os << pa.first << " " << pa.second;
}
 
template <typename T>
std::ostream& operator<<(std::ostream& os, std::vector<T> vec) {
  for (int i = 0; i < vec.size(); i++)os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
 
template<typename T1,typename T2>
inline bool chmax(T1& a,T2 b){return a<b && (a=b,true);}
 
template<typename T1,typename T2>
inline bool chmin(T1& a,T2 b){return a>b && (a=b,true);}
 
long long pow_mod(long long a, long long b, long long mod=-1) {
  if(b==0)return 1;
  if ((a == 0)||(mod!=-1&&(a+mod)%mod==0)) {
    return 0;
  }
  long long x = 1;
  while (b > 0) {
    if (b & 1) {
      x = (mod!=-1)?(x * a) % mod:x*a;
    }
    a = (mod!=-1)?(a * a) % mod:a*a;
    b >>= 1;
  }
  return x;
}

// const long long MOD = 998244353;
const long long MOD = 1e9 + 7;

using ll = long long;
using P=std::pair<long long,long long>;

ll calc2(ll n,ll k,std::vector<ll> a){

  using namespace std;
   	const ll INF = (ll)(1e18)+100;
    sort(a.begin(), a.end());
    ll count[3] = {0};  //0:- 1:0 2:+   負、0、正それぞれの個数
    rep(i, 0,n){
        if(a[i] < 0)    count[0]++;
        else if(a[i] > 0)   count[2]++;
        else            count[1]++;
    }
    ll cdic[3] = {0};  //0:-  1:0  2:+ となるペアの個数、累積をとる
    cdic[0] = count[0]*count[2];
    cdic[1] = cdic[0] + count[1]*(count[0]+count[1]+count[2]) - count[1]*(count[1]+1)/2;
    cdic[2] = cdic[1] + count[0]*(count[0]-1) + count[2]*(count[2]-1);
    ll ans = 0;
    if(k <= cdic[0]){
        //ansが負
        vector<ll>pos;
        vector<ll>neg;
        rep(i, 0,n){
            if(a[i] < 0)        neg.push_back(a[i]);
            else if(a[i] > 0)   pos.push_back(a[i]);
        }
        ll ok = -INF, ng = 0;
        while(ok + 1 < ng){
            ll x = (ok+ng)/2;   //x未満がk未満
            ll ck = 0;
            rep(i,0, pos.size()){ //正を固定して負を二分探索
                ll l = -1, r = neg.size();
                while(l + 1 < r){
                    ll t = (l+r)/2;
                    if(pos[i]*neg[t] < x)   l = t;
                    else                    r = t;
                }
                ck += r;
            }
            if(ck < k)  ok = x;
            else        ng = x;
        }
        ans = ok;
    }else if(k <= cdic[1]){
        //ansが0
    }else{
        //ansが正
        k -= cdic[1];
        vector<ll>pos;
        vector<ll>neg;
        rep(i,0, n){
            if(a[i] < 0)        neg.push_back(a[i]);
            else if(a[i] > 0)   pos.push_back(a[i]);
        }
        rep(i, 0,neg.size())  neg[i] = 0 - neg[i];
        sort(neg.begin(), neg.end());
        ll ok = 0, ng = INF;
        while(ok + 1 < ng){
            ll x = (ok+ng)/2;   //x未満がk未満
            ll ck = 0;
            //pos
            rep(i,0, pos.size()){
                ll l = -1, r = pos.size();
                while(l + 1 < r){
                    ll t = (l+r)/2;
                    if(pos[i]*pos[t] < x)   l = t;
                    else                    r = t;
                }
                ck += r;
                if(pos[i]*pos[i] < x)   ck--;
            }
            //neg
            rep(i, 0,neg.size()){
                ll l = -1, r = neg.size();
                while(l + 1 < r){
                    ll t = (l+r)/2;
                    if(neg[i]*neg[t] < x)   l = t;
                    else                    r = t;
                }
                ck += r;
                if(neg[i]*neg[i] < x)    ck--;
            }
            if(ck/2 < k)  ok = x;
            else        ng = x;
        }
        ans = ok;
    }
    return ans;
}

ll calc1(ll n,ll k,std::vector<ll> a){
  std::vector<ll> plus,minus;
  ll zero=0;
  rep(i,0,n){
    if(a[i]>0){
      plus.push_back(a[i]);
    }else if(a[i]<0){
      minus.push_back(-a[i]);
    }else{
      zero++;
    }
  }

  std::sort(all(plus));
  std::sort(all(minus));

  ll m=minus.size();
  ll p=plus.size();

  auto check=[&](ll key,std::vector<ll>& a,std::vector<ll>& b)->ll{
    ll cnt=0;
    for(ll e:a){
      cnt+=std::upper_bound(all(b),key/e)-b.begin();
    }
    return cnt;
  };

  auto check2=[&](ll key,std::vector<ll>& a,std::vector<ll>& b)->ll{
    ll cnt=0;
    for(ll e:a){
      auto itr=std::upper_bound(all(b),key/e);
      cnt+=itr-b.begin();
      if(itr==b.end()||*itr>e)cnt--;
    }
    return cnt;
  };

  if(k<=m*p){
    ll left=-(1e18+10),right=0;
    while(right-left>1){
      ll mid=(left+right)/2;
      if(check(-mid,minus,plus)>=m*p-k+1)left=mid;
      else right=mid;
    }
    return left;
  }else if(k<=m*p+zero*(2*n-zero-1)/2){
    return 0;
  }else{
    k-=m*p+zero*(2*n-zero-1)/2;
    ll left=0,right=1e18+10;
    while(right-left>1){
      ll mid=(left+right)/2;
      if(check2(mid,minus,minus)/2+check2(mid,plus,plus)/2<k)left=mid;
      else right=mid;
    }
    return right;
  }
}

int main() {
  std::cin.tie(nullptr);
  std::ios::sync_with_stdio(false);

  ll n,k;
  std::cin>>n>>k;

  std::vector<ll> a(n);
  rep(i,0,n)std::cin>>a[i];

  std::cout<<calc2(n,k,a)<<"\n";

  return 0;
}


Measured memory_bytes: 5620