/*
  Compete against Yourself.
  Author - Aryan Choudhary (@aryanc403)
*/

#pragma GCC optimize ("Ofast")
#pragma GCC target ("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize ("-ffloat-store")

#include<iostream>
#include<bits/stdc++.h>
using namespace std;
#define fo(i,n)   for(i=0;i<(n);++i)
#define repA(i,j,n)   for(i=(j);i<=(n);++i)
#define repD(i,j,n)   for(i=(j);i>=(n);--i)
#define all(x) begin(x), end(x)
#define sz(x) (lli)(x).size()
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define endl "\n"

typedef long long int lli;
typedef long double mytype;
typedef pair<lli,lli> ii;
typedef vector<ii> vii;
typedef vector<lli> vi;

clock_t time_p=clock();
void aryanc403()
{
#ifdef ARYANC403
    time_p=clock()-time_p;
    cerr<<"Time Taken : "<<(float)(time_p)/CLOCKS_PER_SEC<<"\n";
#endif
}

#ifdef ARYANC403
#include "/home/aryan/codes/PastCodes/header.h"
#else
    #define dbg(args...)
#endif

const lli INF = 0xFFFFFFFFFFFFFFFL;

lli seed;
mt19937 rng(seed=chrono::steady_clock::now().time_since_epoch().count());
inline lli rnd(lli l=0,lli r=INF)
{return uniform_int_distribution<lli>(l,r)(rng);}

class CMP
{public:
bool operator()(ii a , ii b) //For min priority_queue .
{    return ! ( a.X < b.X || ( a.X==b.X && a.Y <= b.Y ));   }};

void add( map<lli,lli> &m, lli x,lli cnt=1)
{
    auto jt=m.find(x);
    if(jt==m.end())         m.insert({x,cnt});
    else                    jt->Y+=cnt;
}

void del( map<lli,lli> &m, lli x,lli cnt=1)
{
    auto jt=m.find(x);
    if(jt->Y<=cnt)            m.erase(jt);
    else                      jt->Y-=cnt;
}

bool cmp(const ii &a,const ii &b)
{
    return a.X<b.X||(a.X==b.X&&a.Y<b.Y);
}

const lli mod = 1000000007L;
// const lli maxN = 1000000007L;

    lli T,n,i,j,k,in,cnt,l,r,u,v,x,y;
    lli m,z;
    string s;
    vi nn,pp;
    //priority_queue < ii , vector < ii > , CMP > pq;// min priority_queue .

lli chkp(const vi &a,lli val)
{
    lli cnt=0;
    lli i=0,j=sz(a)-1;
    while(i<j)
    {
        while(j>i&&a[j]>val/a[i])
            j--;
        cnt+=j-i;
        i++;
    }
    dbg(a,val,cnt);
    return cnt;
}

lli chkn(const vi &a,const vi &b,lli val)
{
    lli cnt=sz(a)*sz(b);
    lli j=sz(b)-1;
    val--;
    for(auto x:a)
    {
        while(j>=0&&b[j]>val/x)
            j--;
        dbg(val,j,val/x)
        cnt-=j+1;
    }
    // dbg(val,a,b,cnt)
    return cnt;
}

lli chk(lli val)
{
    if(val>0)
        return chkp(pp,val)+chkp(nn,val)+(n-z)*z+z*(z-1)/2+(sz(pp)*sz(nn));
    if(val==0)
        return (sz(pp)*sz(nn))+(n-z)*z+z*(z-1)/2;
    return chkn(pp,nn,-val);
}

int main(void) {
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    // freopen("txt.in", "r", stdin);
    // freopen("txt.out", "w", stdout);
// cout<<std::fixed<<std::setprecision(35);
// cin>>T;while(T--)
{

    cin>>n>>k;
    fo(i,n)
    {
        cin>>in;
        if(in==0)
            z++;
        if(in>0)
            pp.pb(in);
        if(in<0)
            nn.pb(abs(in));
    }
    sort(all(pp));
    sort(all(nn));
    lli l=-1e18-1,r=1e18+1;
    while(r-l>1)
    {
        lli m=l+(r-l)/2;
        if(chk(m)<k)
            l=m;
        else
            r=m;
    }
    cout<<r<<endl;
}   aryanc403();
    return 0;
}


Measured memory_bytes: 2420