#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <limits>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <functional>
#include <iomanip>

using namespace std;

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define eprintf(...) 42
#endif
using ll = long long;
using vll = std::vector<ll>;
using vvll = std::vector<vll>;
using vvvll = std::vector<vvll>;
#define reps(i, S, E) for (ll i = (S); i <= (E); i++)
#define rep(i, N) reps(i, 0, N-1)
#define deps(i, E, S) for (ll i = (E); i >= (S); i--)
#define dep(i, N) deps(i, N-1, 0)
const ll INF = 1LL << 60;
const int INF_INT = 1 << 30;

template<class T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; }return false; }
struct mll {
	static ll MOD;
	ll val;
	mll(ll v = 0) : val(v % MOD) { if (val < 0) val += MOD; }
	mll operator - () const { return -val; }
	mll operator + (const mll &b) const { return val + b.val; }
	mll operator - (const mll &b) const { return val - b.val; }
	mll operator * (const mll &b) const { return val * b.val; }
	mll operator / (const mll &b) const { return mll(*this) /= b; }
	mll operator + (ll b) const { return *this + mll(b); }
	mll operator - (ll b) const { return *this - mll(b); }
	mll operator * (ll b) const { return *this * mll(b); }
	friend mll operator + (ll a, const mll &b) { return b + a; }
	friend mll operator - (ll a, const mll &b) { return -b + a; }
	friend mll operator * (ll a, const mll &b) { return b * a; }
	mll &operator += (const mll &b) { val = (val + b.val) % MOD; return *this; }
	mll &operator -= (const mll &b) { val = (val + MOD - b.val) % MOD; return *this; }
	mll &operator *= (const mll &b) { val = (val*b.val) % MOD; return *this; }
	mll &operator /= (const mll &b) {
		ll c = b.val, d = MOD, u = 1, v = 0;
		while (d) {
			ll t = c / d;
			c -= t * d; swap(c, d);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	mll &operator += (ll b) { return *this += mll(b); }
	mll &operator -= (ll b) { return *this -= mll(b); }
	mll &operator *= (ll b) { return *this *= mll(b); }
	mll &operator /= (ll b) { return *this /= mll(b); }
	bool operator == (const mll &b) { return val == b.val; }
	bool operator != (const mll &b) { return val != b.val; }
	bool operator == (ll b) { return *this == mll(b); }
	bool operator != (ll b) { return *this != mll(b); }
	friend bool operator == (ll a, const mll &b) { return mll(a) == b.val; }
	friend bool operator != (ll a, const mll &b) { return mll(a) != b.val; }
	friend ostream &operator << (ostream &os, const mll &a) { return os << a.val; }
	friend istream &operator >> (istream &is, mll &a) { return is >> a.val; }
	static mll Combination(ll a, ll b) {
		chmin(b, a - b);
		if (b < 0) return mll(0);
		mll c = 1;
		rep(i, b) c *= a - i;
		rep(i, b) c /= i + 1;
		return c;
	}
};
using vmll = std::vector<mll>;
using vvmll = std::vector<vmll>;
using vvvmll = std::vector<vvmll>;
using vvvvmll = std::vector<vvvmll>;

struct Fast {
	Fast() {
		cin.tie(0);
		ios::sync_with_stdio(false);
		cout << fixed << setprecision(std::numeric_limits<double>::max_digits10);
	}
} fast; //cin,cout高速化のおまじない＋桁数指定

ll mll::MOD = (ll)(1e9 + 7);// 998244353ll;

ll numZero = 0;
ll numNeg = 0;
ll numPos = 0;
vector<ll> Aneg(0);
vector<ll> Apos(0);

ll numProductZero = 0;
ll numProductNeg = 0;

//正×正　もしくは　負×負　の場合のx以下の個数を計上
ll solve(ll x, vll &A) {
	ll num = 0;
	ll frontIndex = 0;
	ll numA = A.size();
	ll backIndex = numA - 1;

	while (frontIndex < numA) {
		ll frontHold = A[frontIndex];

		while (backIndex >= 0) {
			ll backHold = A[backIndex];

			if (frontHold * backHold <= x) {
				break;
			}

			backIndex--;
		}

		num += backIndex + 1;
		
		//front同士の組み合わせをキャンセル
		if (frontIndex <= backIndex) {
			num--;
		}

		frontIndex++;
	}
	
	eprintf(" *num:%lld* ", num);

	return num / 2;
}

// index が条件を満たすかどうか
bool isOK(ll x, ll key) { //x以下となる数の個数がkey個以上
	if (x == 0) {
		ll num = numProductNeg + numProductZero;

		eprintf("num:%lld ", num);

		if (num >= key) {
			return true;
		}
		else {
			return false;
		}
	}
	else if (x > 0) {
		if (numProductNeg + numProductZero >= key) {
			eprintf("num:>=%lld ", key);
			return true;
		}

		ll num = numProductNeg + numProductZero;

		//積が正となる数の個数を算出
		num += solve(x, Apos);
		num += solve(x, Aneg);

		eprintf("num:%lld ", num);

		if (num >= key) {
			return true;
		}
		else {
			return false;
		}
	}
	else {
		//積が負となる数のうち、x以下となる個数を計上
		ll negIndex = numNeg - 1;
		ll posIndex = 0;
		ll num = 0;

		while (posIndex < numPos) {
			ll posHold = Apos[posIndex];

			while (negIndex >= 0) {
				ll negHold = Aneg[negIndex];

				if (posHold * negHold > x) {
					break;
				}

				negIndex--;
			}

			num += numNeg - negIndex - 1;

			posIndex++;
		}

		eprintf("num:%lld ", num);

		if (num >= key) {
			return true;
		}
		else {
			return false;
		}
	}
}

// 汎用的な二分探索のテンプレ
ll binary_search(ll key) { //x以下となる数の個数がkey個以上　となるxの最小値を探索する
	ll ng = -1000000000000000000LL; //-10^18
	ll ok = 1000000000000000000LL; //10^18

	// ok と ng のどちらが大きいかわからないことを考慮
	while (abs(ok - ng) > 1) {
		ll mid = (ok + ng) / 2;
		eprintf("mid:%lld ", mid);
		if (isOK(mid, key)) {
			eprintf("ok\n");
			ok = mid;
		}
		else {
			eprintf("ng\n");
			ng = mid;
		}
	}
	return ok;
}


int main() {
	ll N;
	cin >> N;
	ll K;
	cin >> K;
	vector<ll> A(N);
	rep(i, N) {
		cin >> A[i];

		if (A[i] == 0) {
			numZero++;
		}
		else if (A[i] > 0) {
			numPos++;
		}
		else {
			numNeg++;
		}
	}

	Apos.resize(numPos);
	Aneg.resize(numNeg);
	ll iPos = 0;
	ll iNeg = 0;

	rep(i, N) {
		if (A[i] > 0) {
			Apos[iPos] = A[i];
			iPos++;
		}
		else if (A[i] < 0) {
			Aneg[iNeg] = A[i];
			iNeg++;
		}
	}

	std::sort(Apos.begin(), Apos.end());
	std::sort(Aneg.begin(), Aneg.end(), std::greater<ll>());

	numProductZero = (N - 1) * N / 2 - (N - numZero - 1) * (N - numZero) / 2;
	numProductNeg = numNeg * numPos;

	ll result = binary_search(K);

	cout << result << endl;

	return 0;
}


Measured memory_bytes: 3200