#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl
inline int power(int a, int b) {
    int x = 1;
    while (b) {
        if (b & 1) x *= a;
        a *= a;
        b >>= 1;
    }
    return x;
}


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

//_ ***************************** START Below *******************************

vector<pair<int,int>> a;

bool isPossible(int n, double mid){
	
	double x = -1, y = -1;
	for(int i=0; i<n; i++){
		double pos = a[i].first;
		double v = a[i].second;
		
		double l = pos-v*mid;
		double r = pos+v*mid;
		
		if(x == -1 && y == -1){
			x = l;
			y = r;
		}
		else{
			if(y < l ) return false;
			y = min(y, r);
			x = max(x, l);
		}
	}
	return true;
}

double consistency1(int n){
	
	sort(begin(a), end(a));
	
	double precision = 1e-7;
	
	double s = 0, e = INF;
	
	int iterations = 60; // 100 safer
	
	for(int i=0; i<iterations; i++){
		double mid = s + (e-s)/2;
		if(isPossible(n, mid)){
			e = mid;
		}
		else s = mid;
	}
	
	return e;

}



double consistency2(int n){
	
	sort(begin(a), end(a));
	
	double precision = 1e-7;
	
	double s = 0, e = INF;
	double ans = INF;
	
	int iterations = 60; // 100 safer
	
	for(int i=0; i<iterations; i++){
		double mid = s + (e-s)/2;
		if(isPossible(n, mid)){
			ans = min(ans, mid);
			e = mid+precision;
		}
		else s = mid-precision;
	}
	
	return ans;

}









void solve() {
    
    int n;
    cin>>n;
    
    a.resize(n);
    for(int i=0; i<n; i++){
        int x , v;
        cin >> x >> v;
        a[i] = {x, v};
    }
    
    cout << fixed << setprecision(7) << consistency1(n) << endl;
    // cout << fixed << setprecision(7) << consistency1(n) << " " << consistency2(n) << endl;


}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    while (t--) {
        solve();
    }

    return 0;
}