#include <bits/stdc++.h>
#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define VRSORT(v) sort(v.begin(), v.end(),greater<int>());
#define INF 999999999
#define MOD 1000000007
#define M_PI 3.14159265358979323846
#define ALL(X) (X).begin(),(X).end()

#ifdef __LOCAL
    #define DBG(X) cout << #X << " = " << (X) << endl;
    #define SAY(X) cout << (X) << endl;
#else
    #define DBG(X)
    #define SAY(X)
#endif

#ifdef __LOCAL
    #include <filesystem>
    namespace fs = std::filesystem;
#endif

using namespace std;

using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

int dx[]={1, 0, -1, 0, 0};
int dy[]={0, 1, 0, -1, 0};
const int INT_INF = (int)(2e9);
const ll  LL_INF = (ll)(2e18);
const int NIL = -1;
static mt19937 _g(time(nullptr));
 
std::string pad(int num){ char buffer[4]; std::snprintf(buffer, sizeof(buffer), "%03d", num); return buffer;}
inline ll randint(ll a, ll b) { ll w = (_g() << 31LL) ^ _g(); return a + w % (b - a + 1); }
inline void fast_io() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); };
template<typename T> inline T sign(T x) { return T(x > 0) - T(x < 0); }
template<typename T, typename S> inline ostream& operator<<(ostream& os, const pair<T, S> p) { cout << "[" << p.first << ";" << p.second << "]"; return os; }
template<typename T> inline ostream& operator<<(ostream& os, const vector<T>& v) { for (auto el : v) cout << el << " "; return os; }
template<typename T> inline T fetch() { T ret; cin >> ret; return ret; }
template<typename T> inline vector<T> fetch_vec(int sz) { vector<T> ret(sz); for (auto& elem : ret) cin >> elem; return ret; }


ll N,K;
vector<ll> A,Aminus,Aplus;
map<ll, ll> CountSign;
ll k,l,m;

void input(){
  #ifdef __LOCAL
    fs::path p = __FILE__;
    fs::path input,output;
    input = output = p.parent_path();
    input += string("/input/") + string(p.stem()) + string(".txt");
    output += string("/output/") + string(p.stem()) + string(".txt");
    freopen(input.c_str(), "r", stdin);
    freopen(output.c_str(), "w", stdout);
  #endif
  cin >> N >> K;
  REP(i,N){
    ll a;
    cin >> a;
    A.push_back(a);
    CountSign[sign(a)]++;
    if(a>0) Aplus.push_back(a);
    if(a<0) Aminus.push_back(-a);
  }
  VSORT(A)
  VSORT(Aminus)
  VSORT(Aplus)
  k = CountSign[-1];
  l = CountSign[0];
  m = CountSign[1];
}

// 積がx未満の数を数える。
ll C(ll x){
  ll total=0;
  REP(i,N){
    if(A[i]>0){
      // total+=lower_bound(ALL(A),ceil((double)x/A[i]))-A.begin();
      ll left=-1;
      ll right=N;
      while(left+1<right){
        ll c = (left+right)/2;
        if(A[i]*A[c] < x) left=c; else right=c;
      }
      total += left+1;
    }
    else if(A[i]==0){
      if(A[i]<x) total+=N;
    }
    else{
      // total+=A.end()-upper_bound(ALL(A),floor((double)x/A[i]));
      ll left=-1;
      ll right=N;
      while(left+1<right){
        ll c = (left+right)/2;
        if(A[i]*A[c] < x) right=c; else left=c;
      }
      total += N-(left+1);
    }
    if(A[i]*A[i]<x) total--;
  }
  total /= 2;
  return total;
}

ll solve3(ll N, ll K){
  ll inf = (ll)(1e18)+1;
  ll low = -inf;
  ll high = inf;
  while(high-low>1){
    ll mid=(high+low)/2;
    if(C(mid)<K) low = mid; else high = mid;
  }
  cout << low << endl;
  return low;
}

vector<ll> ans;
ll solve_X(int K){
  if(ans.empty()){
    for(int i=0;i<N-1;i++) for(int j=i+1;j<N;j++) ans.push_back(A[i]*A[j]);
    VSORT(ans)
  }
  // for(auto a:ans) cout << a << endl;
  return ans[K-1];
}

ll makeTest(){
  int n,k;
  n = 1e3;
  k = 100;
  vector<ll> a(n);
  REP(i,n) a[i] = randint(-1e9,1e9);
  a[0] = 0;
  a[n-1] = 0;
  N = n;
  K = k;
  A = a;
  VSORT(A)
  return 0;
}

int test(){
  makeTest();
  // cout << A << endl;
  cout << "SOLVE" << endl;
  bool isequal=true;
  REP(i,N) {isequal &= (solve3(N,i+1)==solve_X(i+1));}
  cout << "ANS" << endl;
  cout << boolalpha << isequal << endl;
  return 0;
}

int main()
{
  input();
  solve3(N,K);
  // test();
  return 0;
}


Measured memory_bytes: 5108