#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long
#define db double

template<typename T>
inline void read(T &x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int N = 1e5 + 7;
const db INF = 1e18;

#define ls (rt << 1)
#define rs (ls |  1)

db tr[N << 2];

void ins(int rt, int l, int r, int x, db v){
    if(l == r){
        tr[rt] = v;
        return ;
    }
    int mid = (l + r) >> 1;
    if(x <= mid) ins(ls, l, mid, x, v);
    else ins(rs, mid + 1, r, x, v);
    tr[rt] = min(tr[ls], tr[rs]);
}

db query(int rt, int l, int r, int x, int y){
    if(l == r){
        return tr[rt];
    }
    int mid = (l + r) >> 1;
    if(y <= mid) return query(ls, l, mid, x, y);
    if(x > mid) return query(rs, mid + 1, r, x, y);
    return min(query(ls, l, mid, x, y), query(rs, mid + 1, r, x, y));
}


int x[N];
int y[N];

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int n, k; r(n), r(k);
    for(int i = 1; i <= n; ++i){
        r(x[i]), r(y[i]);
    }
    for(int i = 1; i < n; ++i){
        db t = (db)(y[i + 1] - y[i]) / (x[i + 1] - x[i]);
        ins(1, 1, n - 1, i, t);
    }
    db ans = -INF;
    for(int i = 1; i + k - 2 < n; ++i){
        ans = max(ans, query(1, 1, n - 1, i, i + k - 2));
    }
    printf("%.10lf\n", ans);
    return 0;
}