#define _GLIBCXX_FILESYSTEM
#include <bits/stdc++.h>
using namespace std;
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll long long


double pos[100001];
double v[100001];

int n;

double calc(double x)
{

    double t=-1e17;
    for(int i=0;i<n;i++)
    {
        t=max(t,abs(pos[i]-x)/v[i]);

    }
    return t;
}

int main()
{

     IOS
    cin>>n;
    double mx=INT_MIN;
    for(int i=0;i<n;i++)
    {
        cin>>pos[i]>>v[i];
        mx=max(mx,pos[i]);
    }

    double l=-mx-20;
    double r=mx+20;

    if(n==1)
    {
        cout<<0<<"\n";
        return 0;
    }
    for(int i=0;i<300;i++)
    {

        double mid1=l+(r-l)/3.0;
        double mid2 = r - (r - l) / 3.0;

        double m1=calc(mid1);
        double m2=calc(mid2);

        if(m2<m1)
             l=mid1;
        else
            r=mid2;
    }
    cout<<fixed<<setprecision(10)<<calc(r)<<"\n";

}