// Contest: AtCoder Beginner Contest 155 (https://atcoder.jp/contests/abc155)
// Problem: D: Pairs (https://atcoder.jp/contests/abc155/tasks/abc155_d)


// region {{{ boilerplate
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <chrono>
#include <cstdint>
#include <deque>
#include <exception>
#include <forward_list>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#if __cplusplus >= 201703L
#   include <optional>
#   include <string_view>
#   include <variant>
#endif

using namespace std;

#if __cplusplus >= 201703L
#   define all(a)      begin(a),end(a)
#   define sz(x)       ((int)size(x))
#else
#   define all(a)      (a).begin(),(a).end()
#   define sz(x)       ((int)(x).size())
#endif

#define rep(a, b)      for(int a = 0; a < (b); ++a)
#define reps(a, b, c)  for(int a = (b); a < (c); ++a)
#define trav(a, b)     for(auto& a : b)

using ll = long long;
using ld = long double;
using u64 = uint64_t;
using u32 = uint32_t;

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vvi = vector<vi>;
using vpi = vector<pi>;

#if __cplusplus >= 201703L
#   define MAYBE_UNUSED [[maybe_unused]]
#else
#   define MAYBE_UNUSED
#endif

MAYBE_UNUSED static constexpr int INF = (int)1e9 + 5;
MAYBE_UNUSED static constexpr ll INFL = (ll)1e18 + 5;
MAYBE_UNUSED static mt19937 rng((u32)chrono::duration_cast<chrono::nanoseconds>(chrono::high_resolution_clock::now().time_since_epoch()).count());
//endregion }}}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll n, k; cin >> n >> k; --k;
    vl an, ap;
    int zero = 0;
    rep(i, n) {
        ll ai; cin >> ai;
        if (ai == 0)
            ++zero;
        else
            (ai < 0 ? an : ap).push_back(abs(ai));
    }

    sort(all(an)), sort(all(ap));
    ll tot_neg = sz(ap) * (ll)sz(an);
    ll tot_zero = zero * (ll)(sz(ap) + sz(an)) + (ll)zero * (zero - 1) / 2;
    if (k < tot_neg) {
        ll l = 0, r = INFL;
        while (r - l > 1) {
            ll m = (r + l) / 2;
            int j = sz(an) - 1;
            ll cnt = 0;
            rep(i, sz(ap)) {
                while (j >= 0 && ap[i] * an[j] > m)
                    --j;
                cnt += j + 1;
            }
            (tot_neg - cnt > k ? l : r) = m;
        }
        cout << -r << '\n';
    } else {
        k -= tot_neg;
        if (k < tot_zero)
            cout << "0\n", exit(0);
        k -= tot_zero;
        ll l = 0, r = INFL;
        while (r - l > 1) {
            ll m = (r + l) / 2;
            ll cnt = 0;
            int j = sz(ap) - 1;
            rep(i, sz(ap)) {
                while (j > i && ap[i] * ap[j] > m)
                    --j;
                cnt += max(0, j - i);
            }
            j = sz(an) - 1;
            rep(i, sz(an)) {
                while (j > i && an[i] * an[j] > m)
                    --j;
                cnt += max(0, j - i);
            }
            (cnt > k ? r : l) = m;
        }
        cout << r << '\n';
    }

    return 0;
}

Measured memory_bytes: 2420