#include <bits/stdc++.h>
using namespace std;
int a[100001],b[100001];//原始数据 
double s[100001];//前序和 
struct node
{
	int p;
	double v;
	inline bool operator < (node x)
	{
		return v<x.v;
	}
}c[100001];//HASH
int HASH[100001];
int d[400001];//没错我就是树状数组！！ 
inline int read()
{
	char ch=getchar();
	int x=0;
	while(!isdigit(ch))
		ch=getchar();
	while(isdigit(ch))
	{
		x=x*10+ch-'0';
		ch=getchar();
	}
	return x;
}
int n,k;

inline int sum(int x)
{
	int ans=0;
	while(x)
	{
		ans+=d[x];
		x-=(x&-x); 
	}
	return ans;
}
inline void in(int x)
{
	while(x<=n)
	{
		d[x]++;
		x+=(x&-x);
	}
}
bool judge(double x)
{
	memset(d,0,sizeof(d));
	int i,ans=0;
	for(i=1;i<=n;i++)
	{
		s[i]=s[i-1]+(double)a[i]-(double)b[i]*x;
		c[i].p=i,c[i].v=s[i];
	}
	sort(c+1,c+n+1);//HASH,将数转化为整数； 
	for(i=1;i<=n;i++)
	{
		HASH[c[i].p]=i;
		if(c[i].v==c[i-1].v&&HASH[c[i-1].p]!=0)
			HASH[c[i].p]=HASH[c[i-1].p];
	}
	for(i=1;i<=n;i++)//树状数组闪亮登场!!!! 
	{
		ans+=sum(HASH[i]);
		in(HASH[i]+1);
		if(ans>=k)
			return true; 
	}
	return false;
}
int main()
{
	int i;
	double l=0,r=0,mid;
	n=read(),k=read();
	for(i=1;i<=n;i++)
		a[i]=read();
	for(i=1;i<=n;i++)
	{
		b[i]=read();
		r=max(r,(double)a[i]/b[i]);
	}
	while(l<r&&r-l>0.003)
	{
		mid=(l+r)/2;
		if(judge(mid)) l=mid;
		else r=mid;
	}
	printf("%.2lf",l);
}