#include<bits/stdc++.h>
#define LL long long
#define N 100005
using namespace std;

LL n,k,l,r,mid;
LL a[N],b[N];

bool check(LL x)
{
	LL cnt=0,R=n;
	for(int L=1;L<=n;L++){
		for(;1ll*a[L]*b[R]>x;R--) ;
		cnt+=R;
	}
	return cnt<k;
}

int main()
{
	a[0]=b[0]=-0x3f3f3f3f;
	scanf("%lld%lld",&n,&k);
	for(int i=1;i<=n;i++)
		scanf("%lld",&a[i]);
	for(int i=1;i<=n;i++)
		scanf("%lld",&b[i]);
	sort(a+1,a+n+1);
	sort(b+1,b+n+1);
	l=a[1]*b[1],r=a[n]*b[n];
	while(l<=r){
		mid=l+r>>1;
		if(check(mid)) l=mid+1;
		else r=mid-1;
	}
	printf("%lld",l);
}