#include<bits/stdc++.h>
using namespace std;
const double eps=1e-9;
struct point{
    double x,y;
    point operator+(const point&o)const{return {x+o.x,y+o.y};}
    point operator-(const point&o)const{return {x-o.x,y-o.y};}
    point operator*(const double&o)const{return {x*o,y*o};}
    double operator*(const point&o)const{return x*o.y-y*o.x;}
    double len()const{return sqrt(x*x+y*y);}
};
bool inter(point A,point B,point C,point D){
    double cp1=(B-A)*(C-A),cp2=(B-A)*(D-A);
    if(cp1<-eps&&cp2<-eps||cp1>eps&&cp2>eps)return false;
    cp1=(D-C)*(A-C);cp2=(D-C)*(B-C);
    if(cp1<-eps&&cp2<-eps||cp1>eps&&cp2>eps)return false;
    return true;
}
int main(){
    point A1,A2,B1,B2;double ah,bh,ans=1e9;
    cin>>A1.x>>A1.y>>A2.x>>A2.y>>ah>>B1.x>>B1.y>>B2.x>>B2.y>>bh;
    double aSide=(A2-A1).len(),bSide=(B2-B1).len();
    double aDiag=sqrt(aSide*aSide/2+ah*ah),bDiag=sqrt(bSide*bSide/2+bh*bh);
    double aAlt=sqrt(aSide*aSide/4+ah*ah),bAlt=sqrt(bSide*bSide/4+bh*bh);
    for(int i:{0,1,2,3}){
        point Ap={A1.y-A2.y,A2.x-A1.x};
        point Amid=(A1+A2)*0.5+Ap*0.5;
        for(int j:{0,1,2,3}){
            point Bp={B1.y-B2.y,B2.x-B1.x};
            point Bmid=(B1+B2)*0.5+Bp*0.5;
            for(int x:{0,1}){
                point At=x?A1:(A1+A2)*0.5+Ap*(aAlt/aSide);
                double alen=x?aDiag:0.0;
                for(int y:{0,1}){
                    point Bt=y?B1:(B1+B2)*0.5+Bp*(bAlt/bSide);
                    double blen=y?bDiag:0.0;
                    if(!x&&((Bmid-A1)*(A2-A1)<0||!inter(A1,A2,At,Bt)))continue;
                    if(!y&&((Amid-B1)*(B2-B1)<0||!inter(B1,B2,At,Bt)))continue;
                    ans=min(ans,alen+blen+(Bt-At).len());
                }
            }
            B1=B2+Bp;swap(B1,B2);
        }
        A1=A2+Ap;swap(A1,A2);
    }
    cout<<fixed<<setprecision(9)<<ans<<endl;
    return 0;
}