#include<bits/stdc++.h>
using namespace std;using ll=long long;using vi=vector<int>;using vvi=vector<vi>;using vl=vector<ll>;using vvl=vector<vl>;using P=pair<int,int>;using PL=pair<ll,ll>;using vp=vector<P>;using vpl=vector<PL>;
#define pqueue priority_queue
template<typename T>constexpr auto inf=numeric_limits<T>::max()/2;constexpr int INF=inf<int>,MOD=1000000007;constexpr ll LINF=inf<ll>;
#define _ol3(_1,_2,_3,name,...)name
#define _rep(i,n)_repi(i,0,n)
#define _repi(i,a,b)for(int i=a,i##_l=(b);i<i##_l;++i)
#define REP(...)_ol3(__VA_ARGS__,_repi,_rep,)(__VA_ARGS__)
#define REPR(i,n)for(int i=n-1;i>=0;--i)
#define REPA(i,v)REP(i,(v).size())
#define all(v)(v).begin(),(v).end()
#define rall(v)(v).rbegin(),(v).rend()
#define bit(n)(1ll<<(n))
#define F first
#define S second
#define endl '\n'
#define cho(n,a,b)cout<<((n)?a:b)<<endl
void YES(int n){cho(n,"YES","NO");}void Yes(int n){cho(n,"Yes","No");}void Poss(int n){cho(n,"Possible","Impossible");}
void _print(ostream&){}template<class T,class...U>void _print(ostream&s,const T&t,const U&...u){s<<t<<(sizeof...(u)?' ':'\n');_print(s,u...);}
template<class...T>void print(const T&...t){_print(cout,t...);}template<class...T>void dprint(const T&...t){_print(cerr,t...);}
#ifndef LOCAL
struct osd{template<class T>osd&operator<<(const T&t){return*this;}};osd cer_;
#define dprint(...)
#define cerr cer_
#endif
#define dbg(x) dprint("@l",__LINE__,':',#x,'=',x)
template<class T>bool chmax(T&a,const T&b){bool x=a<b;x?a=b:b;return x;}template<class T>bool chmin(T&a,const T&b){bool x=a>b;x?a=b:b;return x;}
template<class T,class U>ostream&operator<<(ostream&o,const pair<T,U>&p){return o<<p.F<<' '<<p.S;}template<class T,class U>istream&operator>>(istream&i,pair<T,U>&p){return i>>p.F>>p.S;}
template<class T>class iterable{static false_type c(string v);template<class U>static auto c(U v)->decltype(all(v),true_type());static false_type c(...);public:const static bool value=decltype(c(declval<T>()))::value;};
template<class T,enable_if_t<iterable<T>::value,int> =0>ostream&operator<<(ostream&o,const T&v){for(auto&&i:v)o<<i<<' ';return o;}
template<class T>istream&operator>>(istream&i,vector<T>&v){for(T&j:v)i>>j;return i;}template<class T>vector<T>&operator<<(vector<T>&v,const T&t){v.push_back(t);return v;}
template<class T,class U>queue<T,U>&operator<<(queue<T,U>&v, const T&t){v.push(t);return v;}template<class T,class U>queue<T,U>&operator>>(queue<T,U>&v, T&t){t=v.front();v.pop();return v;}
template<class T,class U,class V>pqueue<T,U,V>&operator<<(pqueue<T,U,V>&v, const T&t){v.push(t);return v;}template<class T,class U,class V>pqueue<T,U,V>&operator>>(pqueue<T,U,V>&v, T&t){t=v.front();v.pop();return v;}
template<class T,class U>stack<T,U>&operator<<(stack<T,U>&v, const T&t){v.push(t);return v;}template<class T,class U>stack<T,U>&operator>>(stack<T,U>&v, T&t){t=v.front();v.pop();return v;}
template<class T,class U,class V>set<T,U,V>&operator<<(set<T,U,V>&v,const T&t){v.insert(t);return v;}template<class T,class U,class V>multiset<T,U,V>&operator<<(multiset<T,U,V>&v,const T&t){v.insert(t);return v;}
template<class T,enable_if_t<is_integral<T>::value,int> =0>T mod(T a, T b){if(a>0)return a%b;return b-(-a%b);}template<class T,enable_if_t<is_floating_point<T>::value,int> =0>T mod(T a, T b){if(a>0)return fmod(a,b);return b-fmod(-a,b);}
template<class T,class U>pair<T,U>&operator+=(pair<T,U>&a, pair<T,U>&b){a.F+=b.F;a.S+=b.S;return a;}template<class T,class U>pair<T,U>operator+(const pair<T,U>&a, const pair<T,U>&b){T r=a;return r+=b;}
template<class T,class U>pair<T,U>&operator-=(pair<T,U>&a, pair<T,U>&b){a.F-=b.F;a.S-=b.S;return a;}template<class T,class U>pair<T,U>operator-(const pair<T,U>&a, const pair<T,U>&b){T r=a;return r-=b;}
template<class T,class U>pair<T,U>operator-(const pair<T,U>&a){return mp(-a.F, -a.S);}
template<class T,class U>double std::norm(const pair<T,U>&p){return norm(p.F)+norm(p.S);}template<class T,class U>double std::abs(const pair<T,U>&p){return sqrt(norm(p));}

ll du(ll a, ll b){ // ceil(a/b)
    if(b<0)a*=-1,b*=-1;
    if(a>=0)return (a+b-1)/b;
    return -((-a)/b);
}

ll dd(ll a, ll b){ // floor(a/b)
    if(b<0)a*=-1,b*=-1;
    if(a>=0)return a/b;
    return -(((-a)+b-1)/b);
}

vi a;
ll judge(ll k){ // count <=k
    dprint("k=",k,"--------------------");
    ll r=0;
    if(k<=0 || 1){
        REPA(i,a){
            if(!i)continue;
            if(a[i]==0){
                if(k>=0)r+=i;
            }else if(a[i]>0){
                dbg(dd(k,a[i]));
                r+=upper_bound(a.begin(),a.begin()+i,dd(k,a[i])) - a.begin();
            }else{
                dbg(du(k,a[i]));
                dbg(lower_bound(a.begin(),a.begin()+i, du(k,a[i])) - a.begin());
                r+=a.begin()+i - lower_bound(a.begin(),a.begin()+i, k/a[i]);
            }
            dbg(r);
        }
    // }else{
    //     REPA(i,a){
    //         if(a[i]==0){
    //         }else if(a[i]>0){
    //             r+=upper_bound(a.begin(),a.begin()+i,(k+a[i]-1)/a[i]) - a.begin();
    //         }else{
    //             r+=a.begin()+i - upper_bound(a.begin(),a.begin()+i,-(k/(-a[i]))+1);
    //         }
    //         dbg(r);
    //     }
    }
    //dprint(k,':',r);
    return r;
}

int main(){
    cin.tie(0);ios::sync_with_stdio(0);
    cout<<setprecision(10);
    ll n,k;
    cin>>n>>k;
    a.resize(n);
    cin>>a;
    sort(all(a));
    ll le=-LINF;
    ll ri=LINF;
    ll mi;

    // REP(i, -20, 20)judge(i);
    //return 0;
    while(le+1<ri){
        // dprint(le, ri);
        mi=(le+ri)/2;
        if(judge(mi)>=k)
            ri=mi;
        else
            le=mi;
    }
    cout<<ri<<endl;
    
}



Measured memory_bytes: 1024