#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double ldb;
typedef pair<int,int> pii;
const int MAXN = 1e5 + 5;

int n,d;
array<int,2> p[MAXN];

ldb calc(int i,int j)
{
	return ldb(p[i][1] - p[j][1]) / (p[i][0] - p[j][0]);
}

bool check(ldb lim)
{
	static int sta[MAXN], f[MAXN];
	int tp = 0;
	for(int i=n; i>=1; --i)
	{
		f[i] = 1;
		while(tp && calc(i, sta[tp]) >= lim)
			f[i] = max(f[i], f[sta[tp]] + 1), --tp;
		sta[++tp] = i;
		if(f[i] >= d) return 1;
	}
	return 0;
}

int main(void)
{
	scanf("%d%d",&n,&d);
	for(int i=1; i<=n; ++i)
		scanf("%d%d",&p[i][0],&p[i][1]);
	
	ldb l = -1e9, r = 1e9;
	for(int T=1; T<=100; ++T)
	{
		ldb mid = (l+r)/2;
		if(check(mid)) l = mid;
		else r = mid;
	}
	printf("%.20lf\n",l);
	return 0;
}