#pragma target("avx")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> P;
typedef vector<ll> V;
typedef unordered_map<ll, ll> U_MAP;
typedef priority_queue<ll> pq;
typedef priority_queue<ll, vector<ll>, greater<ll>> rpq;
const int INF = 1e9, MOD = 1e9 + 7, ohara = 1e6 + 10;
const ll LINF = 1e18;

#define rep(i, n) for (ll(i) = 0; (i) < (int)(n); (i)++)
#define rrep(i, a, b) for (ll i = (a); i < (b); i++)
#define rrrep(i, a, b) for (ll i = (a); i >= (b); i--)
#define all(v) (v).begin(), (v).end()
#define Size(n) (n).size()
#define Cout(x) cout << (x) << endl
#define doublecout(a) cout << fixed << setprecision(15) << a << endl;
#define fi first
#define se second
#define m_p make_pair
#define p_b push_back
string to_string(string s) { return '"' + s + '"'; }
string to_string(const char* s) { return to_string((string)s); }
string to_string(bool b) { return (b ? "true" : "false"); }
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto& x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)

//------ Believe yourself as a genius!!!!!! ------

int dy[] = {1, 0, -1, 0};
int dx[] = {0, 1, 0, -1};
// int dy[]={-1,0,1,-1,1,-1,0,1};int dx[]={-1,-1,-1,0,0,1,1,1};
string alph("abcdefghijklmnopqrstuvwxyz"), s;
ll n, cnt, ans, a[ohara], b, c, d, tmp, m, h, w, x, y, sum, k, q, kage, zyo;
ll nega, posi, posi_bor, nega_bor;

int main(void) {
  cin.tie(0);
  cout.tie(0);
  ios::sync_with_stdio(false);

  cin >> n >> k;
  rep(i, n) cin >> a[i];
  rep(i, n) {
    if (a[i] < 0)
      nega++;
    else if (a[i] > 0)
      posi++;
  }
  rep(i, n) {
    if (a[i] > 0) {
      posi_bor = i;
      break;
    }
  }
  rrrep(i, n - 1, 0) {
    if (a[i] < 0) {
      nega_bor = i;
      break;
    }
  }
  sort(a, a + n);

  ll le = -LINF, ri = LINF, mid;
  while (ri - le > 1) {
    mid = (le + ri) / 2;
    cnt = 0;
    if (mid < 0) {
      rep(i, n) {
        if (a[i] >= 0) continue;
        kage = (mid + a[i] + 1) / a[i];
        // kage以上なら良い
        ll le2 = i + 1, ri2 = n - 1, mid2;
        if (ri2 < le2) continue;
        tmp = -1;
        while (ri2 - le2 > 1) {
          mid2 = (le2 + ri2) / 2;
          if (a[mid2] < kage)
            le2 = mid2;
          else
            ri2 = mid2;
        }
        rrep(j, max(le2 - 2, i + 1), min(ri2 + 2, n)) {
          if (a[j] >= kage) {
            tmp = j;
            break;
          }
        }
        if (tmp == -1) continue;
        cnt += n - 1 - tmp + 1;
      }
    } else {
      ll add = 0;
      rep(i, n) {
        if (a[i] < 0) {
          kage = mid / a[i];
          // kage以上なら良い
          ll le2 = i + 1, ri2 = n - 1, mid2;
          if (ri2 < le2) continue;
          tmp = -1;
          while (ri2 - le2 > 1) {
            mid2 = (le2 + ri2) / 2;
            if (a[mid2] < kage)
              le2 = mid2;
            else
              ri2 = mid2;
          }
          rrep(j, max(le2 - 2, i + 1), min(ri2 + 2, n)) {
            if (a[j] >= kage) {
              tmp = j;
              break;
            }
          }
          if (tmp == -1) continue;
          cnt += n - 1 - tmp + 1;
          // if (mid == 0) Cout(cnt);
          // Cout(le2);
          continue;
        }
        if (a[i] == 0) {
          cnt += n - 1 - i;
          // if (mid == 0) Cout(cnt);
          continue;
        }
        zyo = mid / a[i];
        // kage以上なら良い
        ll le2 = i + 1, ri2 = n - 1, mid2;
        if (ri2 < le2) continue;
        tmp = -1;
        while (ri2 - le2 > 1) {
          mid2 = (le2 + ri2) / 2;
          if (a[mid2] <= zyo)
            le2 = mid2;
          else
            ri2 = mid2;
        }
        // debug(zyo);
        rrrep(j, min(ri2 + 2, n - 1), max(le2 - 2, i + 1)) {
          if (a[j] <= zyo) {
            tmp = j;
            break;
          }
        }
        if (tmp == -1) continue;
        cnt += tmp - (i + 1) + 1;
        // if (mid == 0) Cout(cnt);
      }
    }
    if (cnt >= k)
      ri = mid;
    else
      le = mid;

    // Cout(mid);
    // cout << mid << " " << cnt << "\n";
  }
  // cout << nega << " " << posi << "\n";
  Cout(ri);
  return 0;
}

Measured memory_bytes: 1792