
#include
#include
#include
#include
#include
#define pb push_back
using namespace std;
typedef long long LL;
const int N=2e5+5;
const LL INF=1e18;
vectorpos,neg;
int main()
{
	int n;
	LL k;
	scanf("%d%lld",&n,&k);
	for(int i=1;i<=n;i++)
	{
		int a;
		scanf("%d",&a);
		if(a>0)pos.pb(a);
		else if(a<0)neg.pb(a);
	}
	sort(pos.begin(),pos.end());
	sort(neg.begin(),neg.end());
	LL ne=1LL*neg.size()*pos.size();
	LL po=1LL*pos.size()*(pos.size()-1)/2+1LL*neg.size()*(neg.size()-1)/2;
	LL ze=1LL*n*(n-1)/2-ne-po;
	if(k<=ne)
	{
		LL l=-INF,r=0,ans;
		while(l<=r)
		{
			LL mid=(l+r)/2,num=0;
			for(int i=0;imid);
				num+=x;
			}
			for(int i=0;imid);
				num+=neg.size()-x;
			}
			assert(num%2==0);
			num=num/2+ze+ne;
			if(num