#include<iostream>
using namespace std;

int main(){
    double maxs = 0;
    int n; cin >> n;
    double prevt, prevd; cin >> prevt >> prevd;
    for(int i=1; i<n; ++i){
        double a,b; cin >> a >> b;
        maxs = max(maxs, (b-prevd)/(a-prevt));
        prevt = a;
        prevd = b;
    }
    cout << maxs;
}