#include <iostream>
#include <string.h>
#include <stdio.h>
#include <cmath>

using namespace std;
#define maxx 100
#define INF 10000000

struct Node
{
    double x;
    double y;
} p[maxx]; ///每扇门的终点 起点 和门的两个端点的平面坐标

struct EDGE
{
    int u;
    int v;
} Edge[maxx*maxx]; ///存构造的边    因为之前是孤立的点

int n;      ///n个墙
double wX[20];  ///输入每堵墙的横坐标
double py[20][4]; ///每堵墙横坐标对应的纵坐标 0 1 2 3

double g[maxx][maxx];  ///存邻接矩阵  配合dis[]的
double dis[maxx];  ///beg到其他点的最短距离

int Psize;  ///边的数量
int Esize;  ///点的数量

double Dis(Node a,Node b)  ///计算亮点之间的距离
{
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}

double cross(double x1,double y1,double x2,double y2,double x3,double y3)  ///判断（x3,y3）与（x1,y1）（x2,y2）是否交叉
{
    return (x2-x1)*(y3-y1)-(x3-x1)*(y2-y1);
}

bool IsOk(Node a,Node b)  ///判断两点之间是否可以连线
{
   if(a.x>=b.x)
   return false;
   bool falg=true;
   int i=0;
   while(wX[i]<=a.x&&i<n)
   i++;
   while(wX[i]<b.x&&i<n)
   {
       if(cross(a.x,a.y,b.x,b.y,wX[i],0)*cross(a.x,a.y,b.x,b.y,wX[i],py[i][0])<0
        ||cross(a.x,a.y,b.x,b.y,wX[i],py[i][1])*cross(a.x,a.y,b.x,b.y,wX[i],py[i][2])<0
        ||cross(a.x,a.y,b.x,b.y,wX[i],py[i][3])*(cross(a.x,a.y,b.x,b.y,wX[i],10))<0)
        {
            falg=false;
            break;
        }
        i++;
   }
   return falg;
}

double Bellman(int beg,int end)
{
    for(int i=0;i<maxx;i++)
    dis[i]=INF;
    dis[beg]=0;
    bool EX=true;
    for(int i=0;i<=Psize&&EX;i++)
    {
        EX=false;
        for(int j=0;j<Esize;j++)
        {
            if(dis[Edge[j].u]<INF&&dis[Edge[j].v]>(dis[Edge[j].u]+g[Edge[j].u][Edge[j].v]))
            {
                dis[Edge[j].v]=(dis[Edge[j].u]+g[Edge[j].u][Edge[j].v]);
                EX=true;
            }
        }
    }
    return dis[end];
}


int main()
{
    while(scanf("%d",&n)!=EOF)
    {
        if(n==-1)
            break;
        p[0].x=0;
        p[0].y=5;
        Psize=1;
        for(int i=0; i<n; i++)
        {
            cin>>wX[i];
            for(int j=0; j<4; j++)
            {
                p[Psize].x=wX[i];
                cin>>p[Psize].y;
                py[i][j]=p[Psize].y;
                Psize++;
            }
        }
        p[Psize].x=10;
        p[Psize].y=5;
        for(int i=0; i<=Psize; i++)
        {
            for(int j=0; j<=Psize; j++)
            {
                g[i][j]==INF;
            }
        }
        Esize=0;
        for(int i=0; i<=Psize; i++)
        {
            for(int j=i+1; j<=Psize; j++)
            {
                if(IsOk(p[i],p[j]))
                {
                    g[i][j]=Dis(p[i],p[j]);
                    Edge[Esize].u=i;
                    Edge[Esize].v=j;
                    Esize++;
                }
            }
        }
        printf("%.2lf\n",Bellman(0,Psize));
    }
    return 0;
}