#include <iostream>
#include <iomanip>
#include <algorithm>
#include <complex>
#include <utility>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <tuple>
#include <cmath>
#include <bitset>
#include <cctype>
#include <set>
#include <map>
#include <unordered_map>
#include <numeric>
#include <functional>
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(ll i=ll(a);i<ll(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define PRINT(V) cout << V << "\n"
#define SORT(V) sort((V).begin(),(V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
inline void Yes(bool condition){ if(condition) PRINT("Yes"); else PRINT("No"); }
template<class itr> void cins(itr first,itr last){
    for (auto i = first;i != last;i++){
        cin >> (*i);
    }
}
template<class itr> void array_output(itr start,itr goal){
    string ans = "",k = " ";
    for (auto i = start;i != goal;i++) ans += to_string(*i)+k;
    if (!ans.empty()) ans.pop_back();
    PRINT(ans);
}
ll gcd(ll a, ll b) {
    return a ? gcd(b%a,a) : b;
}
const ll INF = 1e15;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
typedef pair<ll,ll> P;
const ll MAX = 200010;
constexpr ll nx[8] = {1,0,-1,0,-1,-1,1,1};
constexpr ll ny[8] = {0,1,0,-1,-1,1,-1,1};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n,k,a;
    cin >> n >> k;
    vector<ll> m,p;
    ll zero = 0;
    rep(i,n){
        cin >> a;
        if (a > 0) p.push_back(a);
        else if (a == 0) zero++;
        else m.push_back(-a);
    }
    SORT(m);
    SORT(p);
    zero = zero*(n-zero)+zero*(zero-1)/2;
    ll ms = m.size(),ps = p.size();
    if (k <= ms*ps){
        ll l = 0,r = 1e18;
        while(r-l > 1){
            ll mid = (l+r)/2;
            ll big = 0,same = 0;
            rep(i,ms){
                ll key = mid/m[i]+1;
                if (mid%m[i] == 0) same += upper_bound(all(p),key-1)-lower_bound(all(p),key-1);
                if (p[ps-1] < key) continue;
                big += p.end()-lower_bound(all(p),key);
            }
            //cout << mid << " " << big << " " << same << endl;
            if (k <= big) l = mid;
            else if (k <= big+same){
                PRINT(-mid);
                return 0;
            }
            else r = mid;
        }
        PRINT(-r);
    }
    else if (k <= ms*ps+zero){
        PRINT(0);
    }
    else{
        k -= ms*ps+zero;
        ll l = 0,r = 1e18;
        while(r-l > 1){
            ll mid = (l+r)/2;
            ll small = 0,same = 0;
            rep(i,ms-1){
                ll key = (mid%m[i] ? mid/m[i] : mid/m[i]-1);
                small += upper_bound(m.begin()+i+1,m.end(),key)-m.begin()-i-1;
                if (mid%m[i] == 0) same += upper_bound(m.begin()+i+1,m.end(),key+1)-lower_bound(m.begin()+i+1,m.end(),key+1);
            }
            rep(i,ps-1){
                ll key = (mid%p[i] ? mid/p[i] : mid/p[i]-1);
                small += upper_bound(p.begin()+i+1,p.end(),key)-p.begin()-i-1;
                if (mid%p[i] == 0) same += upper_bound(p.begin()+i+1,p.end(),key+1)-lower_bound(p.begin()+i+1,p.end(),key+1);
            }
            //cout << mid << " " << small << " " << same << endl;
            if (k <= small) r = mid;
            else if (k <= small+same){
                PRINT(mid);
                return 0;
            }
            else l = mid;
        }
        PRINT(r);
    }
}



Measured memory_bytes: 2420