#include <bits/stdc++.h>
using namespace std;

#define CPP_STR(x) CPP_STR_I(x)
#define CPP_CAT(x,y) CPP_CAT_I(x,y)
#define CPP_STR_I(args...) #args
#define CPP_CAT_I(x,y) x ## y

using i8  = int8_t;
using u8  = uint8_t;
using i16 = int16_t;
using u16 = uint16_t;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;

using f32 = float;
using f64 = double;

#define FOR(i, start, end) for(i64 i = (start), CPP_CAT(i,xxxx_end)=(end); i < CPP_CAT(i,xxxx_end); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPS(i, n) for(i64 i = 1; i <= n; ++i)
#define RREP(i, n) for(i64 i = n - 1; i >= 0 ; --i)
#define RREPS(i, n) for(i64 i = n; i >= 1; --i)

#define ALL(f,c,...) (([&](decltype((c)) cccc) { return (f)(std::begin(cccc), std::end(cccc), ## __VA_ARGS__); })(c))

#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );

#define pb push_back
#define mp make_pair
#define F first
#define S second

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; }

template<typename C>
i64 SIZE(const C& c) { return static_cast<i64>(c.size()); }

template<typename T, size_t N>
i64 SIZE(const T (&)[N]) { return static_cast<i64>(N); }


struct ProconInit {
    static constexpr int IOS_PREC = 15;
    static constexpr bool AUTOFLUSH = false;

    ProconInit() {
        cin.tie(nullptr);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(IOS_PREC);
        if(AUTOFLUSH)
            cout << unitbuf;
    }
} PROCON_INIT;


#define MAX_N 200000
typedef pair<i64, i64> P;
i64 N, K;
vector<i64> Neg;
vector<i64> Pos;
i64 zero_cnt;

bool comp_abs(P x, P y) {
  return abs(x.F) < abs(y.F);
}

// K番目の積がx
// <=> x以下の積の個数がK以上

i64 neg_pos() {
  // Negative * Positive
  // x: [-10^18, 0)

  sort(Neg.begin(), Neg.end(), greater<i64>()); // -1 -2 -3 ...
  sort(Pos.begin(), Pos.end(), greater<i64>()); // 3 2 1 ...

  i64 lb = -1e18 - 1;
  i64 ub = 0;
  while (ub - lb > 1) {
    i64 mid = (lb + ub) / 2;

    // 積がmid以下となる負数*正数の組み合わせを数える
    // -2 3 3
    // -4 3 3
    i64 cnt = 0;
    i64 l = 0; // Negを動く
    i64 r = 0; // Posを動く
    while (l < Neg.size()) {
      while (r < Pos.size() && Neg[l] * Pos[r] <= mid) {
        r++;
      }
      cnt += r;
      l++;
    }

    if (cnt >= K) {
      ub = mid;
    } else {
      lb = mid;
    }
  }

  return ub;
}

i64 solve() {
  i64 cnt = 0;

  i64 mink;
  // neg * pos
  if (K <= Neg.size() * Pos.size()) {
    if (Neg.size() > 0 && Pos.size() > 0) {
      return neg_pos();
    }
  } else {
    cnt += Neg.size() * Pos.size();
  }

  // 0 * (Neg|Pos)
  if (zero_cnt > 0) {
    cnt += zero_cnt * (Neg.size() + Pos.size()) + (zero_cnt * (zero_cnt - 1)) / 2;
    if (K <= cnt) {
      return 0;
    }
  }

  // neg * neg or pos * pos
  sort(Pos.begin(), Pos.end());
  sort(Neg.begin(), Neg.end(), greater<i64>());

  i64 pos_max = 0;
  if (Pos.size() >= 2) {
    pos_max = Pos[Pos.size() - 1] * Pos[Pos.size() - 2];
  }
  i64 neg_max = 0;
  if (Neg.size() >= 2) {
    neg_max = Neg[Neg.size() - 1] * Neg[Neg.size() - 2];
  }

  // Neg, Posからx以下の積となる組み合わせの個数を数えてKを2分探索で求める
  i64 lb = 0;
  i64 ub = max(pos_max, neg_max) + 1;
  i64 mid, n;
  while (ub - lb > 1) {
    mid = (lb + ub) / 2;

    n = 0;
    i64 l = 0;
    i64 r = Neg.size() - 1;
    while (r - l > 0) {
      while (l < r && Neg[l] * Neg[r] > mid) {
        r--;
      }
      n += r - l;
      l++;
    }

    l = 0;
    r = Pos.size() - 1;
    while (r - l > 0) {
      while (l < r && Pos[l] * Pos[r] > mid) {
        r--;
      }
      n += r - l;
      l++;
    }

    if (cnt + n >= K) {
      ub = mid;
    } else {
      lb = mid;
    }
  }
  return ub;
}

int main() {
  cin >> N >> K;
  i64 a;
  zero_cnt = 0;
  REP(i, N) {
    cin >> a;
    if (a == 0) {
      zero_cnt++;
    } else if (a > 0) {
      Pos.pb(a);
    } else {
      Neg.pb(a);
    }
  }

  i64 res = solve();
  cout << res << endl;

  return 0;
}

Measured memory_bytes: 2420