#include <bits/stdc++.h>

void Yes() {
    std::cout << "YES" << "\n";
    return;
}

void No() {
    std::cout << "NO" << "\n";
    return;
}

template<typename T>
void out(T x) { std::cout << x << "\n"; }

using namespace std;
using ll = long long;
using PII = pair<double, int>;

const int N = 2e5 + 10;
int nxt[N];
double x[N], y[N];
void Solve() {
    ll n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        cin >> x[i] >> y[i] , nxt[i] = i + 1;

    set<PII>st;
    for (int i = 2; i <= n; i++)
    {
        st.insert({(y[i] - y[i - 1]) / (x[i] - x[i - 1]), i - 1 });
    }
//    for(auto p:st) {
//        cout<<p.first<<"\n";
//    }
    for (int i = m + 1; i<= n; i++) {
        auto now = *st.begin();
//        cout<<st.size()<<" ";
//        cout<<now.first<<"\n";
        st.erase(now);
        int id = now.second;

        int nid = nxt[id];
        int nnid = nxt[nid];
//        cout<<id<<" "<<nid<<" "<<nnid<<"\n";
        if(nnid <= n ) {
            st.erase({(y[nnid] - y[nid]) / (x[nnid] - x[nid]),nid});
            st.insert({(y[nnid] - y[id]) / (x[nnid] - x[id]),id});
        }
        nxt[id] = nxt[nxt[id]];
    }
    cout<<(*st.begin()).first<<"\n";
}

signed main() {
    cout<<fixed<<setprecision(10);
    int t = 1;
//    cin>>t;
    while (t--)
        Solve();
}