#include<bits/stdc++.h>

using namespace std;

long double Tf, Vf, Hf, Td, Vd, Hd;
long double vp;


long double jed(){
    long double ta=sqrt(2*Hf);
    long double sa= Vf*ta;
    long double taprim=sa/Vd;
    return Td+taprim*2;
}

long double trzy(){
    long double b = (Td-Tf+vp);
    long double c = Hf - 0.5*(Td - Tf)*(Td - Tf);
    long double tc;
    if(0<b*b - c*4){
        tc= b - sqrt(b*b - c*4);
        tc/=2;
    }
    else tc = b/2;

    long double sc=tc*Vf;
    return Td+tc+sc/Vd;
}




int main(){
    ios_base::sync_with_stdio(0);
    cin>>Tf>>Vf>>Hf>>Td>>Vd>>Hd;

    long double ret=-1;
    cout<<setprecision(10);
    cout<<fixed;

    vp=sqrt(Hd*6);
    long double s0=(Td-Tf)*Vf;
    if(Vd<=Vf){
        cout<<jed();
        return 0;
    }
    long double t1=s0/(Vd-Vf);
    long double X = Hf - 0.5*(t1+Td-Tf)*(t1+Td-Tf);
    if(X<=0)ret = jed();
    else if(X > Hd){
        long double t2 = sqrt(Hf*2- Hd*2);
        if(t2 > vp/3+Td-Tf){
            long double tb=sqrt(Hf*2- Hd*2);
            long double sb=Vf*tb;
            long double tbprim=sb/Vd;
            ret=Tf+tb+tbprim;
        }
        else{
            ret=trzy();
        }
    }
    else{
        long double tw= vp-sqrt(vp*vp - X*6);
        tw/=3;
        if(t1 >= tw)ret = Td + t1*2;
        else ret=trzy();
    }

    cout<<ret;

    return 0;
}