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

#define ll                 long long
#define ull                unsigned long long
#define pii                pair<int, int>
#define pll                pair<ll, ll>
#define mp                 make_pair
#define ff                 first
#define ss                 second
#define sz(x)              (int) x.size()
#define all(v)             v.begin(), v.end()
#define fill(a, b)         memset(a, b, sizeof(a))
#define endl               '\n'

template <typename T> inline void smin(T &a, T b) {a = a < b ? a : b;}
template <typename T> inline void smax(T &a, T b) {a = a > b ? a : b;}

#define error(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args); }
void err(istream_iterator<string> it) {cout << endl;}
template<typename T, typename... Args> void err(istream_iterator<string> it, T a, Args... args) {
    cerr << *it << " = " << a << ", ";
    err(++it, args...);
}

template <typename T> inline void Int(T &n) {
    n = 0; int f = 1; register int ch = getchar();
    for (; !isdigit(ch); ch = getchar()) if (ch == '-') f = -1;
    for (; isdigit(ch); ch = getchar()) n = (n << 3) + (n << 1) + ch - '0';
    n = n * f;
}

template <typename T, typename TT> inline void Int(T &n, TT &m) { Int(n); Int(m); }
template <typename T, typename TT, typename TTT> inline void Int(T &n, TT &m, TTT &l) { Int(n, m); Int(l); }

const int mod = (int) 1e9 + 7;

inline int add(int a, int b) {a += b; return a >= mod ? a - mod : a;}
inline int sub(int a, int b) {a -= b; return a < 0 ? a + mod : a;}
inline int mul(int a, int b) {return (ll) a * b % mod;}

const int inf = (int) 2e9 + 5;
const ll  Inf = (ll) 1e18 + 5;
const int N   = (int) 2e5 + 5;

std::vector<ll> a, b;
ll n, k;

int bs(std::vector<ll>& tem, int l, ll x, ll target) {
    int low = l, high = sz(tem) - 1;
    int ans = 0;
    while (low <= high) {
        //error("bs")
        int mid = (low + high) >> 1;
        if (x * tem[mid] <= target) ans = mid - l + 1, low = mid + 1;
        else high = mid - 1;
    }
    return ans;
}


int bs2(std::vector<ll>& tem, int l, ll x, ll target) {
    int low = l, high = sz(tem) - 1, r = sz(tem);
    int ans = 0;
    while (low <= high) {
        //error("bs2")
        int mid = (low + high) >> 1;
        if (x * tem[mid] <= target) ans = r - mid, high = mid - 1;
        else low = mid + 1;
    }
    return ans;
}

ll zero;

int ok(ll x) {
    ll cnt = 0;
    for (int i = 0; i < sz(a); i++) {
        cnt += bs2(b, 0, a[i], x);
        cnt += bs(a, i + 1, a[i], x);
    }
    for (int i = 0; i < sz(b); i++) {
        cnt += bs(b, i + 1, b[i], x);
    }
    if(x >= 0) cnt += ((zero * (zero - 1)) / 2) + (zero * 1LL * (sz(a) + sz(b)));
    if (cnt >= k) return 1;
    return 0;
}

int solve() {
    Int(n, k);
    for (int i = 0; i < n; i++) {
        ll x; Int(x);
        if (x < 0) a.push_back(x);
        else if(x == 0) zero++;
        else b.push_back(x);
    }
    sort(all(a));
    reverse(all(a));
    sort(all(b));
    ll ans = 0;
    ll low = -Inf, high = Inf;
    while (low <= high) {
        //error(low)
        ll mid = (low + high) / 2;
        if (ok(mid)) ans = mid, high = mid - 1;
        else low = mid + 1;
    }
    printf("%lld\n", ans);
    return 0;
}

int main() {
    //ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int test = 1, tc = 0;
    //Int(test);
    //cin >> test;
    while (test--) {
        //printf("Case %d: ", ++tc);
        solve();
    }
    return 0;
}

Measured memory_bytes: 2420