#include <bits/stdc++.h>

using namespace std;
#define int long long
#define app push_back
#define all(x) (x).begin(),(x).end()
#ifdef LOCAL
#define debug(...) [](auto...a){ ((cout << a << ' '), ...) << endl;}(#__VA_ARGS__, ":", __VA_ARGS__)
#else
#define debug(...)
#endif
#ifdef LOCAL
#define __int128 long long
#endif // LOCAL
#define y1 rtgerf
#define pt pair<double,double>
#define x first
#define y second
const double eps=1e-9;
pt operator+(pt a,pt b) {return pt(a.x+b.x,a.y+b.y);}
pt operator*(double c,pt a) {return pt(a.x*c,a.y*c);}
const int inf=1e18;
int32_t main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int n;cin>>n;
    double tot1=0,tot2=0;
    vector<pt> v;
    for(int i=0;i<n;++i)
    {
        int x,y,z,t;cin>>x>>y>>z>>t;tot1+=x*y;tot2+=z*t;
        double to=y+t;
        v.app({to*x,to*z});
    }
    sort(all(v),[&](pt o1,pt o2) {return o1.first*o2.second>o1.second*o2.first;});
    vector<pt> u;
    double s=0;for(auto h:v) {s+=h.first;}
    u.app({s,0});
    for(auto h:v)
    {
        pt o=u.back();o.x-=h.x;o.y+=h.y;u.app(o);
    }
    vector<pt> al=u;
    vector<pt> o=u;
    for(int i=0;i<o.size()-1;++i)
    {
        if(o[i].x>tot1 && o[i+1].x<tot1)
        {
            double c1=(tot1-o[i+1].x)/(o[i].x-o[i+1].x);double c2=(o[i].x-tot1)/(o[i].x-o[i+1].x);
            al.app(c1*o[i]+c2*o[i+1]);
        }
        if(o[i].y<tot2 && o[i+1].y>tot2)
        {
            double c1=(tot2-o[i+1].y)/(o[i].y-o[i+1].y);double c2=(o[i].y-tot2)/(o[i].y-o[i+1].y);
            al.app(c1*o[i]+c2*o[i+1]);
        }
    }
    double res=1e18;
    for(auto h:al)
    {
        if(h.x<=tot1+eps && h.y<=tot2+eps)
        {
            res=min(res,h.x+h.y);
        }
    }
    cout<<setprecision(25)<<res;
    return 0;
}