#include <bits/stdc++.h>
#define rep(i,l,r) for(int i=l; i<=r; i++)
#define per(i,r,l) for(int i=r; i>=l; i--)
#define IOS {cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);}
using namespace std;

typedef long long ll;
typedef pair<int,int> P;

const double eps = 1e-7;
const int N = 100010;

int x[N], y[N];
int n, k, tree[N]; 

double c[N], a[N], f[N];


int query(int x) {
    int mx = 0;
    for (int i = x; i; i -= i&-i) {
        mx = max(mx, tree[i]);
    }
    return mx;
}

void update(int x, int tt) {
    for (int i = x; i<= n; i+= i&-i) {
        tree[i] = max(tree[i], tt);
    }
}

bool check(double mm) {
    // memset(tree, 0, sizeof(tree));
    rep (i, 1, n) a[i] = y[i] - x[i] * mm, f[i] = 4e18;
    // sort(c+1, c+n+1);
    // int mx = 0;
    // rep (i, 1, n) {
    //     int t = lower_bound(c+1, c+n+1, a[i]) - c;
    //     int tmp = query(t) + 1;
    //     update(t, tmp);
    //     mx = max(mx, tmp);
    //     if (mx>=k) return 1;
    // }
    // return mx >= k;
    rep (i, 1, n) {
        int t = upper_bound(f+1, f+n+1, a[i]) - f;
        f[t] = min(f[t], a[i]);
    }
    return f[k] < 3e18;

}

int main() {
    scanf("%d%d", &n, &k);
    rep (i, 1, n) {
        scanf("%d%d", &x[i], &y[i]);
    }
    double l = -1e9, r = 1e9, ans = -1;
    while (r-l > eps) {
        double mid = (l+r)/2;
        if (check(mid)) l = mid, ans = mid;
        else r = mid;
    }
    printf("%.10lf", ans);
    return 0;
}