#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <climits>#include <string>#include <iostream>#include <map>#include <cstdlib>#include <list>#include <set>#include <queue>#include <stack>#include <sstream>using namespace std;typedef long long LL;const int maxn = 2000;const int maxm = 2000 * 2000; const double INF = 1e30;const double eps = 1e-7;struct Point {    double x,y;    Point(double x = 0,double y = 0):x(x),y(y) {}};Point str(0,5),end(10,5);vector<Point> p,pw;double dist[maxn][maxn],d[maxn];int N,M;int dcmp(double x) {    if(fabs(x) < eps) return 0;    if(x < 0) return -1;    return 1;}Point operator - (Point a,Point b) {    return Point(a.x - b.x,a.y - b.y);}double Cross(Point a,Point b) {    return a.x * b.y - a.y * b.x;}double Dot(Point a,Point b) {    return a.x * b.x + a.y * b.y;}bool SegmentCross(Point a1,Point a2,Point b1,Point b2) {    double c1 = Cross(a2 - a1,b1 - a1),           c2 = Cross(a2 - a1,b2 - a1),           c3 = Cross(b2 - b1,a1 - b1),           c4 = Cross(b2 - b1,a2 - b1);    return dcmp(c1) * dcmp(c2) < 0 && dcmp(c3) * dcmp(c4) < 0;}bool nonecross(Point a1,Point a2) {    for(int i = 0;i < pw.size();i += 2) {        if(SegmentCross(a1,a2,pw[i],pw[i + 1]))            return false;    }    return true;}void solve() {    //构建邻接矩阵    M = p.size();    for(int i = 0;i < M;i++) {        for(int j = i + 1;j < M;j++) {            if(nonecross(p[i],p[j])) {                dist[i][j] = dist[j][i] =                     sqrt(Dot(p[i]-p[j],p[i]-p[j]));            } else dist[i][j] = INF;        }    }    //bellman-ford    for(int i = 0;i < M;i++) d[i] = INF;    d[0] = 0;    for(int i = 0;i < M;i++) {        for(int j = 0;j < M;j++) {            for(int k = 0;k < M;k++) if(dist[j][k] < INF) {                if(d[j] < INF) {                    d[k] = min(d[k],d[j] + dist[j][k]);                }            }        }    }    printf("%.2f\n",d[M - 1]);}int main() {    while(cin >> N,N != -1) {        p.clear();        pw.clear();        p.push_back(Point(0,5));        for(int i = 1;i <= N;i++) {            double posx,posy;            cin >> posx;            pw.push_back(Point(posx,0));            for(int j = 0;j < 4;j++) {                cin  >> posy;                p.push_back(Point(posx,posy));                pw.push_back(Point(posx,posy));            }            pw.push_back(Point(posx,10));        }        p.push_back(Point(10,5));        solve();    }    return 0;}