#include <iostream>

#include <cstdio>

#include <cstring>

#include <vector>

#include <cmath>

#include <algorithm>

using namespace std;

#define eps 1e-8

#define PI 3.1415926

double xl,xr,yl,yr;

double judge(double tx,double ty)

{

    if(tx < xl&&ty < yl)

    return sqrt((tx-xl)*(tx-xl)+(ty-yl)*(ty-yl));

    else if(tx >= xl&&tx <= xr&&ty >= yr)

    return ty - yr;

    else if(tx >= xl&&tx <= xr&&ty <= yl)

    return yl - ty;

    else if(tx > xr&&ty > yr)

    return sqrt((tx-xr)*(tx-xr)+(ty-yr)*(ty-yr));

    else if(ty >= yl&&ty <= yr&&tx >= xr)

    return tx - xr;

    else if(ty >= yl&&ty <= yr&&tx <= xl)

    return xl - tx;

    else if(tx > xr&&ty < yl)

    return sqrt((tx-xr)*(tx-xr)+(ty-yl)*(ty-yl));

    else if(tx < xl&&ty > yr)

    return sqrt((tx-xl)*(tx-xl)+(ty-yr)*(ty-yr));

    return ;

}

int main()

{

    double sx,sy,rx,ry,r;

    int i;

    double tx,ty,minz,temp;

    while(scanf("%lf%lf",&sx,&sy)!=EOF)

    {

        if(sx == &&sy == ) break;

        minz = ;

        scanf("%lf%lf%lf",&rx,&ry,&r);

        scanf("%lf%lf%lf%lf",&xl,&yl,&xr,&yr);

        if(xl > xr) swap(xl,xr);

        if(yl > yr) swap(yl,yr);

        for(i = ;i < ;i ++)

        {

            tx = rx+r*cos(i*1.0*PI/);

            ty = ry+r*sin(i*1.0*PI/);

            temp = sqrt((tx-sx)*(tx-sx) + (ty-sy)*(ty-sy));

            minz = min(minz,temp+judge(tx,ty));

        }

        printf("%.2f\n",minz);

    }

    return ;

}