#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <numeric>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)
using namespace std;
typedef long long int ll;

// clang-format off
#ifdef _DEBUG_
#define dump(...) do{ cerr << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; PPPPP(__VA_ARGS__); cerr << endl; } while(false)
template<typename T> void PPPPP(T t) { cerr << t; }
template<typename T, typename... S> void PPPPP(T t, S... s) { cerr << t << ", "; PPPPP(s...); }
#else
#define dump(...)
#endif
template<typename T> vector<T> make_v(size_t a, T b) { return vector<T>(a, b); }
template<typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v(ts...))>(a, make_v(ts...)); }
template<typename T>
bool chmin(T &a, T b) { if (a > b) {a = b; return true; } return false;}
template<typename T>
bool chmax(T &a, T b) { if (a < b) {a = b; return true; } return false;}
// clang-format on

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n;
    ll k;
    cin >> n >> k;
    vector<ll> mi, pl;
    int zeros = 0;
    REP(i, 0, n) {
        ll a;
        cin >> a;
        if (a < 0) {
            mi.push_back(a);
        } else if (a > 0) {
            pl.push_back(a);
        } else {
            zeros++;
        }
    }
    ll ms = mi.size(), ps = pl.size();
    ll ans = 0;
    dump(ms * ps, k, ms * ps + (ms + ps) * zeros + zeros * (zeros - 1) / 2);

    if (ms * ps < k && k <= ms * ps + (ms + ps) * zeros + zeros * (zeros - 1) / 2) {
        cout << 0 << endl;
        return 0;
    }
    if (ms * ps < k) {  // plusのほうに解がある
        sort(pl.begin(), pl.end());
        REP(i, 0, ms) {
            mi[i] = -mi[i];
        }
        sort(mi.begin(), mi.end());
        k -= (ms * ps + (ms + ps) * zeros + zeros * (zeros - 1) / 2);
        dump(k);
        ll l = 0, r = (1e+18) + 1000100;
        while (l <= r) {
            ll mid = l + (r - l) / 2;
            ll cnt = 0;
            REP(i, 0, ps) {
                ll b = (mid) / pl[i];
                int it = upper_bound(pl.begin() + i + 1, pl.end(), b) - (pl.begin() + i + 1);
                cnt += max(it, 0);
            }
            REP(i, 0, ms) {
                ll b = mid / mi[i];
                int it = upper_bound(mi.begin() + i + 1, mi.end(), b) - (mi.begin() + i + 1);
                cnt += max(it, 0);
            }
            dump(cnt, mid);
            if (cnt < k) {
                l = mid + 1;
            } else {
                ans = mid;
                r = mid - 1;
            }
        }
    } else {  // minusのほうに解がある
        sort(pl.begin(), pl.end());
        REP(i, 0, ms) {
            mi[i] = -mi[i];
        }
        sort(mi.begin(), mi.end());
        k = ms * ps - (k - 1);  // 上からk番目
        ll l = 0, r = (1e+18) + 1000100;
        dump(k);
        while (l <= r) {
            ll mid = l + (r - l) / 2;
            ll cnt = 0;
            REP(i, 0, ms) {
                ll b = mid / mi[i];
                int it = upper_bound(pl.begin(), pl.end(), b) - pl.begin();
                cnt += max(it, 0);
            }
            dump(cnt, mid);
            if (cnt < k) {
                l = mid + 1;
            } else {
                ans = mid;
                r = mid - 1;
            }
        }
        ans = -ans;
    }
    cout << ans << endl;
    return 0;
}


Measured memory_bytes: 2420