#include<bits/stdc++.h>
using namespace std;
#define int long long
#define N 100010
int n,K;
int x[N],y[N];
int check(double k)
{
	for(int ci=1;ci<=n;ci++)
	{
		int cnt=1;
		int px=x[ci],py=y[ci];
		for(int i=ci+1;i<=n;i++)
		{
			double nk=(y[i]-py)*1.0/(x[i]-px);
			if(nk<=k)
			{
				cnt++;
				px=x[i];py=y[i];
			}
		}
		if(cnt>=K) return 1;
	}
	return 0;
}
signed main()
{
	//freopen("a.in","r",stdin);
	//freopen("aa.out","w",stdout);
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin>>n>>K;
	for(int i=1;i<=n;i++)
	{
		cin>>x[i]>>y[i];
	}
	double l=-1e9,r=1e9;
	for(int i=1;i<=80;i++)
	{
		double m=(l+r)/2;
		if(check(m))
		{
			r=m;
		}
		else
		{
			l=m;
		}
	}
	cout<<setprecision(10)<<l<<"\n";
	return 0;
}